Keywords

The field of public health is often described as the science and art of preventing disease, prolonging life, and promoting health (Winslow, 1920). To achieve these ends, public health research is often focused on the relationships between exposures and health outcomes, and in turn, this research informs public health interventions and policy. Important examples include the relationships between smoking and lung cancer, poor nutrition and stunted childhood growth, and sugary beverages and diabetes. Historically, exposures of most interest to public health researchers are those that might be classified as environmental (e.g., housing, water, sanitation) or biological (e.g., specific pathogens, nutrients, or contaminants). Likewise, key outcomes of interest have generally been those related to physical health, morbidity, and mortality.

Throughout the twentieth century, the focus on environmental and biologic exposures allowed public health scientists, researchers, and policymakers to make tremendous gains in human survival. Polio immunization, smallpox eradication, clean drinking water, improved sanitation, and safer food production are just a few of many landmark achievements. These laudable gains in public health gave way to new empirical projects that explored features of a person’s life beyond the environmental and biologic exposures that impact health and well-being. These features, often called the social determinants of health, include aspects of life such as socioeconomic status, housing, education, and healthcare access. Similarly, outcomes of interest have extended beyond physical health to incorporate mental health and social well-being. This expanded consideration of exposures and outcomes offers promising vistas of inquiry for public health research, fostering curiosity about other features of the human experience that might profoundly shape human health and well-being.

Building on these themes, a growing line of inquiry examines the role religion/spirituality plays in population health (Idler, 2014; Oman, 2018). Early empirical efforts to advance understanding of religion/spirituality and health were somewhat limited by the use of cross-sectional data or small sample sizes. However, in recent years, empirical exploration has grown far more rigorous in its use of longitudinal data, larger sample sizes, and increasingly sophisticated analytical techniques. The resulting body of evidence, highlighted in this chapter, suggests that religious/spiritual factors play significant and complex roles in human health and well-being (Oman, 2018; Balboni et al., 2022).

Of course, most people do not engage in religious community and spiritual practices chiefly to improve their physical or mental health. For most, the driving motivations are connection to God or the transcendent and orienting one’s life around a sacred reality (see Davis et al., Chap. 18, this volume). Against this backdrop, a reasonable question might be: If the chief ends of religious communities and persons are in God, mature spiritual states of being, or eternal flourishing, why then do we observe religious/spiritual associations with so many outcomes pertaining to forms of flourishing in the here and now? What is it about religious/spiritual factors that drive these gains in health and well-being? In addition to mechanisms such as community support and shared practices, could it also be that religious virtues, although ultimately pointed toward spiritual and eternal ends, simultaneously cultivate improved corporeal health and well-being? Or, put another way, what role might religious or theological virtues play in promoting human flourishing?

In this chapter, we attempt an answer to these questions with an inquiry focused on the Christian theological virtues of faith, hope, and love. We recognize that these virtues are shared by a number of religions and cultures and that different religious traditions embrace a variety of other religious virtues. Yet out of respect for the complex and distinct ways that various faith traditions approach these concepts, we have limited ourselves to one faith tradition (that itself is highly diverse; see Hodge et al., Chap. 10, this volume). We begin by defining the theological virtues from a historical Christian perspective and by summarizing empirical evidence of associations between faith, hope, and love and subsequent health and well-being. We reflect on aspects of these virtues that are (and are not) captured by current measures and on what might be needed to improve measurement going forward. We describe the role of religious communities in fostering these virtues in the modern context—faith in an era of an increasing sense of meaninglessness, hope in an era of increasing despair and deaths of despair, and love in an era of increasing division. Last, we discuss potential implications for public health and human flourishing.

What Are the Theological Virtues?

A virtue might be understood as a habit in accord with reason to attain the good. For the theological virtues, the object of that good is God (Aquinas, 1948). In the Christian tradition, the theological virtues of faith, hope, and love are extoled throughout the Old and New Testaments, and across history and cultures, theologians have identified them as the seminal virtues (among many) in the life of a Christian. The notion of virtue predated Christianity. The ancient Greeks had a long-running discourse on virtues, most notably the Four Cardinal virtues (of wisdom, justice, fortitude, and temperance) described in Plato’s Republic (Plato & Lane, 2007). From the Greeks (Socrates, Plato, and Aristotle), to the Romans (Cicero and Seneca), to philosophers and theologians from the Jewish (Philo) and Christian traditions (St. Augustine and St. Thomas Aquinas), the idea of virtue, defined broadly as a habit of human rightness (Pieper, 1966), became a basic component of consciousness that seeped its way deep into the soil of Western thought (Pieper, 1966, 1997). Hence, in approaching the concepts of faith, hope, and love, Christian theologians committed to divine revelation have grappled with ways these concepts mapped onto existing notions of virtue—and the ways in which they differed. For example, thirteenth century philosopher and theologian St. Thomas Aquinas concentrated much of his intellectual work on the integration of classic Greek philosophy (particularly that of Aristotle) with Christian theology. In his massive theological work, the Summa Theologiae, Aquinas outlined why faith, hope, and love were understood as essentially “theological” in nature:

Such like principles [faith, hope, and love] are called “theological virtues”: first, because their object is God, inasmuch as they direct us aright to God: secondly, because they are infused in us by God alone: thirdly, because these virtues are not made known to us, save by Divine revelation, contained in Holy Writ. (Aquinas, 1948, IaIIae Q. 62 a.1)

Building on the work of St. Thomas Aquinas, twentieth century philosopher Josef Pieper has described theological virtues as “the enobling of man’s nature that entirely surpasses what he [or she] ‘can be’ of himself [or herself]” (Pieper, 1997, p. 99). Pieper (1997) goes on to argue that theological virtues have a supernatural dimension, because they are grounded in and realized only in participation with the Divine. In other words, a theological virtue has its source and fulfillment in God (Pieper, 1997, p. 100).

Throughout Christian history, the nature and expression of the theological virtues have been an ongoing intellectual and spiritual project, including discussion about the proper ordering of the virtues in relation to one another (Summa Theologiae, IaIIae Q. 62 a. 4). The theological virtues are also deeply valued in other religious traditions, including ways that both align with and diverge from Christian interpretations (for an expanded discussion on virtue, see Ratchford et al., Chap. 4, this volume). Although exploring such streams of discourse goes beyond the aims and scope of the present chapter, it remains the case that most Christian traditions across history have extoled faith, hope, and love as three virtues that are worthy of their “theological” distinction and are essential markers and mechanisms of spiritual growth in the Christian life. They are arguably therefore worthy not only of theological reflection but also of empirical study.

Faith

In the New Testament book of Hebrews, the author writes, “Now faith is the assurance of things hoped for, the conviction of things not seen” (English Standard Version Bible, 2001, Hebrews 11:1). Building on this passage, St. Thomas Aquinas added: “Faith is a habit of mind, whereby eternal life is begun in us, making the intellect assent to what is not apparent” (Summa Theologiae, IaIIae Q. 4 a.1). He also described how faith perfects the intellect (the power in us that is concerned with truth) by elevating and perfecting human reason, so that human persons can understand their faith and judge it to be true (Summa Theologiae IIaIIae QQ 1-16). Faith might thus be understood as the habit of mind to believe in God and all that God has revealed.

Measurement

A number of existing measures attempt to assess faith or belief explicitly (Hill & Hood, 1999), some of which use a tradition-specific approach to assess specific elements of faith (e.g., Fullerton & Hunsberger, 1982; VanderWeele et al., 2021, 2022). Other faith-related items are included in scales that aim to capture elements of spiritual well-being or belief across a range of traditions (e.g., the Spiritual Well-Being Scale [Paloutzian & Ellison, 1982] and Brief Multidimensional Measure of Religiousness and Spirituality [Idler et al., 2003]) (also, see an extended list of measures in Appendix 25.S1, Appendix 7.S1, and Appendix 7.S2). Although many of these scales are intermittently employed (in full or in part) in medical and public health research, the vast majority of studies using these items are cross-sectional in nature (Koenig, 2012), making it difficult to infer causality, due to the analysis of data from a single time point.

Given these considerations and the limitations of the available data and research, perhaps the most substantive and well-researched proxy of faith is religious service attendance. Indeed, for many people, it is their faith (or their search for faith) that draws them into participation in a religious community (Bonhoeffer, 2009). Religious service attendance is admittedly a very crude proxy for faith; however, many large-scale studies often include a question about the frequency of a person’s religious service attendance, which allows for a robust window into the relationship between faith and health. Of course, people may attend services for social reasons, rather than because of faith, and faith may be present to some degree in those not attending (e.g., those who suffer from an illness or injury that keeps them from religious service participation). But for many, it is their faith that brings them back to their religious community week after week, and it is also often the religious community that helps uphold, support, and strengthen their faith.

Empirical Evidence

As noted earlier in the chapter, religious community participation is associated with a number of key health and well-being indicators. For example, longitudinal studies with control for baseline confounders and outcomes have produced strong evidence for the effects of religious service attendance on better outcomes for suicide, smoking, substance use disorders, cancer and cardiovascular disease survival, divorce, social support, meaning and purpose, life satisfaction, charitable giving, volunteering, and civic engagement (e.g., see Aksoy et al., 2021; Chen & VanderWeele, 2018; Li et al., 2018; Lim & Putnam, 2010; Strawbridge et al., 1997; VanderWeele et al., 2016; see Appendix 25.S2, for summaries of all the longitudinal studies reviewed in this chapter; also, see Appendix 18.S2 for summaries of many other longitudinal studies of religiousness/spirituality). Below we examine a few of the studies that shed light on the relationship between religious community participation and health.

In their study, Li et al. (2016) used longitudinal data from the first wave of the Nurses’ Health Study to examine the relationship between attendance at religious services and subsequent mortality among a sample of over 74,000 women between 1992 and 2012. After adjusting for a wide range of demographic covariates, lifestyle factors, and medical history, religious service attendance was associated with 33% reduction in all-cause mortality, as well as significant reductions in cardiovascular and cancer mortality. Li et al. (2016) found that social support, optimism, depressive symptoms, and smoking each explained some of the effect. Another study using the same dataset found that attending religious services once a week or more was associated with a fivefold lower rate of suicide, relative to those who never attended religious services (hazard ratio = 0.16; 95% CI: 0.06–0.46; VanderWeele et al., 2016).

Whereas the Nurses’ Health Study is comprised of predominantly White participants, a study conducted with data from the Black Women’s Health Study similarly found that attending religious services several times a week was associated with substantially lower rate of death (mortality rate ratio = 0.64, 95% CI: 0.51–0.80), compared to those who never attended services (VanderWeele et al., 2017). Even more recent studies have also employed sensitivity analyses for unmeasured confounding, and these analyses indicated it was unlikely the results were due entirely to unmeasured factors (VanderWeele, 2021; VanderWeele & Ding, 2017). Furthermore, meta-analyses of longitudinal studies examining the effect of religious service participation have found a 27% (95% CI: 16%–37%) reduction in all-cause mortality risk (Chida et al., 2009) and a significant improvement in mental health (Garssen et al., 2021) for people who attended services at least weekly, compared to those who did not attend at all.

Section Summary

The cumulative evidence between religious community participation and subsequent health and well-being has led some to ask whether the medical and public health communities might consider encouraging participation in religious community for those who already positively self-identify with a religious or spiritual tradition (VanderWeele et al., 2021). Whereas the evidence for this dimension of faith might be increasingly clear, there remains far more that is not well understood about the nature of faith and how it operates in a person’s life over time. The literature on longitudinal studies examining the effects on the health of specific religious beliefs (not to mention of faith itself, theologically understood) is essentially nonexistent. In some ways, it is remarkable that an indicator as crude as frequency of religious service attendance is so predictive of numerous health and well-being outcomes. As new measures of religious faith perhaps emerge in the years ahead, it will be important to remain attentive to the ways each religious tradition approaches the topic of faith—what faith entails and the kinds of thought and action it motivates—such that participants “hear” their own traditions echoed in the wording and emphasis of survey questions (see Hill et al., Chap. 7, this volume).

Hope

The theological virtue of hope orients life to one’s ultimate end in God, and it enables one to lean on God’s help in the midst of human inability and insufficiency (Pieper, 1997). Speaking of this reality in more poetic terms, the Hebrew prophet Isaiah writes: “But those who hope in the Lord will renew their strength. They will soar on wings like eagles; they will run and not grow weary, they will walk and not be faint” (New International Version Bible, 2015; Isaiah 40:31). This dialectic between strength and weakness is characterized well in St. Thomas Aquinas’s writing about hope as a desire for some good that arises out of the perception this future good is difficult but not impossible to attain (Summa Theologiae IIaIIae Q. 17). Speaking to the inherent tensions embedded within theological hope, Pieper wrote: “hope presupposes not only magnanimity but also humility” (Pieper, 1997, p. 127). Theological hope might thus be understood as the habit of fixing one’s attention on one’s future happiness in God and on God as providing the means to attain that end, even amidst difficulties. Whereas these themes are deeply embedded in the Christian tradition of theological hope, hope is often characterized quite differently in its common usage and in much of the empirical literature to date.

Measurement

The dominant measure of hope used in psychological research is Charles Snyder’s Adult Hope Scale (Snyder et al., 1991), which is based on Snyder’s cognitive theory of hope and thus views hope as arising from two interrelated cognitive dimensions: agency and pathways (Snyder, 1994; Snyder et al., 1991). In his conception, agency refers to determination and commitment to help a person move toward their goals, and pathways refer to a person’s perceived ability to reach those goals and formulate new plans when obstacles arise. Some have critiqued Snyder’s emphasis on agency by pointing out the way that hope implies confrontation with the limits of one’s agency (Miceli & Castelfranchi, 2010); however, his measure of hope has been widely used to evaluate associations with psychosocial, physical, and well-being outcomes (Snyder, 2000).

Empirical Evidence

The current body of research around hope has found strong associations with a range of positive outcomes, including emotional adjustment, life satisfaction, positive affect, social support, sense of purpose, and quality of life (Snyder, 2000). Conversely, hopelessness has been associated with increased risk of poor mental health outcomes, including anxiety, depression, and post-traumatic stress disorder (Gerard & Booth, 2015; Weinberg et al., 2016). However, once again, most of these studies are cross-sectional.

The topic of hope is not new to those in the field of positive psychology, but in the field of public health, explorations of hope are much less common. A recent exception is Long and Kim et al.’s (2020b) longitudinal study of nearly 13,000 older US adults. This study explored the relationship between levels of hope and a wide range of subsequent physical health and well-being outcomes (Long et al., 2020b). The analysis controlled for baseline levels of hope, baseline levels of the outcomes, and a rich set of demographic, physical, and psychological factors. Long and colleagues found that participants with a higher sense of hope exhibited a range of better physical health outcomes over time, including 16% lower risk of all-cause mortality, fewer subsequent chronic conditions, and reduced likelihood of cancer and chronic pain. For health behaviors, those with higher hope had an increased likelihood of engaging in subsequently more physical activity and reduced probability of experiencing subsequent sleep problems. In line with existing psychological research on hope, the study found strong positive associations with all indicators of subsequent psychological and social well-being, including higher life satisfaction, sense of purpose, and social integration, as well as lower depression and loneliness. The study also explored what gives rise to hope, finding several predictors that included physical health, health behaviors (e.g., physical activity), social factors (e.g., frequency of contact with friends, volunteering), and all dimensions of psychological well-being and distress. Because many predictors of hope were modifiable, Long, Kim, and colleagues (2020b) suggested that public health programs consider the promotion of hope-enhancing features of people’s lives, which in turn could improve long-term population health and well-being.

Section Summary

The measure of hope used in the study described above was comprised of four statements about hopelessness, meaning that the study assessed participants’ hopefulness by the extent to which they rejected these statements. Although Long and Kim et al. (2020b) found meaningful results, there remains a clear need to press further into what is meant by hope in a philosophical and theological sense, as well as to explore how hope differs from optimism—a term used liberally as a synonym of hope but which is arguably distinct (Bury et al., 2016). There is arguably no measure yet available for the assessment of the theological virtue of hope. For people from the Christian tradition, theological hope points toward a more final and powerful fulfillment of the good, and this hope is itself mysteriously grounded in the birth, life, death, and resurrection of Jesus Christ. Such ideas are distinctive to the Christian faith and not yet reflected in current measures of hope.

Love

Love is considered the highest theological virtue in the Christian tradition. St. Thomas Aquinas noted that whereas faith gives way to vision and hope gives way to possession, love endures—and continues in perfect form when a person is fully united with God (Summa Theologiae IIaIIae Q. 23). But what is love? How might it be defined? Many theologians broadly conceive of love as a desire for and/or commitment to the good of others, yet it remains an understandably challenging task to deliminate a word used to describe everything from one’s enduring affection for a hamburger to one’s devotion to a spouse or God. In light of this challenge, theologian Nicholas Thomas Wright has quipped: “The English word ‘love’ is trying to do so many different jobs at the same time that someone really ought to sit down with it and teach it how to delegate” (Wright, 2012, p. 183).

Although the definition of the word “love” is unquestionably varied across disciplines (e.g., Fredrickson, 2014), philosophers and theologians have suggested it may have a common core—namely, that we use “love” when one or both of two desires are consistently present: a desire for good for the beloved and/or the desire for some form of union with the beloved (Stump, 2006; Summa Theologiae I.II Q. 26.4). In fact, a case can be made that all ordinary language uses of “love” denote a disposition either (i) toward desiring a perceived good or towards desiring union with it (either as an end itself or with it being a source of delight in itself) or (ii) toward desiring good for a particular object for its own sake (VanderWeele, 2021). The theological virtue of love involves both these dispositions, with God as its object. Hence, under this construal, the theological virtue of love could thus be defined as: the habit of desiring union with God as its own end and of desiring good for God’s sake. Under a Christian understanding, this would also, by implication, entail love for one’s neighbor as part of God’s will (Summa Theologiae II.II Q. 25), and thus it would entail the habit of desiring good for one’s neighbor for their own sake and final union with one’s neighbor in God as an end in itself.

Measurement

Despite repeated calls for public health to undertake an epidemiology of love (Levin, 2000, 2007), such a line of research has yet to coalesce, due in part to the wide range of scales used to measure love and those scales’ disparate definitions, philosophical assumptions, and emphases. Among the hundreds (perhaps thousands) of love-related items that are sprinkled across surveys employed in social, psychological, and health science research, some of the more commonly used measures include the Measurement of Romantic Love Scale (Rubin, 1970), Love Attitude Scale (Hendrick & Hendrick, 1986), and Passionate Love Scale (Hatfield & Sprecher, 1986). (See Appendix 25.S1 for an extended list.) However, the of lack of standardized measures and validated definitions of love, as well as the diversity of views about love across disciplines, continue to make comparison or shared understanding difficult to achieve.

Empirical Evidence

Using available measures, many studies have found significant relationships between forms of love and health/well-being (Graham, 2011; Levin, 2001). The vast majority of studies to date have been cross-sectional in nature, meaning that in addition to the challenges of measurement, there is also the potential for reverse causality. To that end, we focus our discussion on a selection of rigorous longitudinal studies that have examined two forms of love (forgiveness and parental love) and their effect on subsequent health and well-being (see an extended discussion on social integration and marriage in Appendix 25.S1).

Forgiveness

Forgiveness, which might be understood as replacing ill-will toward a perceived offender with goodwill toward that offender (Worthington, 2020), does not mean that someone either forgoes the pursuit of a just outcome or excuses wrongdoing. However, it does release the injured party from harboring the pain of resentment, suppression, and anger. To date, a large body of psychological studies have demonstrated positive outcomes associated with increased forgiveness (Worthington & Wade, 2020), inspiring public health researchers to explore how this unique form of love might positively impact population health (Toussaint et al., 2015).

For example, a series of recent studies used cohort data from the Nurses’ Health Study II (NHSII) to examine the role of forgiveness and subsequent health and well-being, controlling for a large range of covariates and for prior values of outcome variables. One study found that people who forgave others more frequently had better outcomes in a number of areas, including higher levels of positive affect (β = 0.18; 95% CI: 0.15–0.21) and more social integration (β = 0.15; 95% CI: 0.13–0.17). Higher forgiveness also led to lower levels of psychological distress, including lower levels of depression, anxiety, hopelessness, and loneliness (Long et al., 2020c). Two other studies—one incorporating data from the nurses’ children and another examining the role of self-forgiveness and divine forgiveness on health and well-being—similarly found that higher forgiveness was associated with greater psychosocial well-being and less psychological distress (Chen et al., 2018; Long et al., 2020a).

Parental Love

The love beween parents and children is one of the more universal forms of love. In a recent study using longitudinal data from the Midlife in the United States study, 3,929 participants were followed across a 10-year period (Chen et al., 2019b). This study found that parental warmth during childhood (a proxy for love) was positively associated with increased flourishing (β = 0.21; 95% CI = 0.18–0.25) and inversely related to several negative health behavior outcomes (such as smoking and drug use) during adulthood. Another robust longitudinal study that employed data from the Growing Up Today study examined various aspects of parenting and outcomes for children (Chen et al., 2019a). This study found that, among young adults, greater parental authoritativeness (high levels of both warmth and discipline) led to greater emotional well-being, fewer depressive symptoms, and lower risk of overeating and risky behaviors. Importantly, when parental warmth was considered independently, it was found to be the most important aspect of parenting and subsequent child well-being. These studies suggest that the childhood experience of loving warmth between parent and child is a pivotal factor in a child’s future flourishing.

Section Summary

Whereas there is indeed evidence that love impacts health in generally positive ways, a great deal remains unknown, due to the limits of cohesive definitions and measures of love, as well as to the relatively few robust longitudinal explorations of love and its long-term effects on health and well-being. More attention is also needed concerning nonromantic forms of love that might apply across different relationships, such as love of neighbor, love of God, love of friends, and even love of enemies, because these types of dyads contain varying forms of appropriate union and contribution toward the good of the other (Stump, 2006; VanderWeele, 2021b). Further work might also consider the proper ordering of loves, for example, that love of neighbor flows from one’s love for God (Aquinas, 1948).

Prospects and Limitations

As noted above, the measures used in existing empirical research related to faith, hope, and love are essentially only capturing specific facets of—or very crude proxies for—the corresponding theological virtues. To the best of our knowledge, there has been no longitudinal research employing multi-item measures that are intended to assess the theological virtues of faith, hope, and love. The existing longitudinal studies might then be seen as studies of the effects of faith, of hope, and of love as theological virtues, rather than as studies of these virtues themselves. More work on measurement development and refinement remains to be done, and to that end, we have tried to provide above some tentative construct definitions of each of the theological virtues (because proposed construct definitions are too often lacking and arguably are a critical part of sound measure development). The theological virtues are, of course, oriented principally toward God, which of course affect a host of other things in a person’s life as well, and it is these effects that the existing empirical research helps uncover.

The Role of Religious Communities in Fostering the Theological Virtues

This chapter was written in the midst of the COVID-19 pandemic where the sense of societal suffering was palpable, painful, and pervasive. Prior to the pandemic, rates of meaningless (Stein et al., 2017), deaths of despair (Case & Deaton, 2020), and deepening divisions along polticial, racial, and ideological lines (Brooks, 2019) were all intensifying—trends that were only exacerbated during the pandemic and its attendant challenges. Although it is true that religious communities can themselves be the source of great pain and suffering, the evidence we present in this chapter suggests that religious communities might also be one of the most important resources in our time. They can play a vital role in helping heal some of our collective pain, suffering, and division (see Wang et al., Chap. 29, this volume). It is in these sacred spaces that faith is nurtured—faith that can instill a deeper sense of meaning and purpose to help ground the meaninglessness that overcomes so many people. It is in religious community that the message of hope—deep hope, improbable hope, resounding hope—can push against the despair that drives so much suffering and premature death. And it is in religious community that the love of God and love of neighbor can take root, offering a radical alternative to the divisions that threaten to shred our homes, our communities, our nation, and our world.

Implications for Public Health Research and Practice—And Human Flourishing

We close with three recommendations for improved public health research and practice. The first need is for better measurement of faith, hope, and love, informed by philosophical and theological discourse and in conversation with other social science research. The second need is for empirical research that employs rigorous methodology, including the use of longitudinal data, sufficient covariate control, and control for baseline outcomes where possible (VanderWeele, 2021c). Not only should future empirical work consider the long-term impacts of faith, hope, and love on human health and well-being, but it should also explore the factors that give rise to these virtues, which represent the principal ends of many religious communities. Finally, there is a need to promote the development and refinement of ideas that lead to human flourishing. If faith, hope, and love are demonstrably linked to human health and well-being, then public health, government, and faith community leaders can play a role in promoting these goods from their various vantage points. This is not a governmental universal “prescription of religion” but rather an encouragement to take seriously the empirical work that demonstrates avenues toward human flourishing and to support communities, programs, and policies that are already working toward these ends.