The term spiritual dates back to the 14th century to the Latin term spiritualitas, derived from spiritus, meaning soul, breath, or life force [209]. This life force was believed to drive all aspects of life. Today, spirituality refers to the belief that there is a power or powers outside one's own that transcend understanding [7]. It has been stated that there are three dimensions of spirituality [8]:

During the Age of Enlightenment in the 1700s, the intellectual climate was marked by two movements: rationalism and empiricism [17]. Rationalism emphasized that the primary authority for truth is rationality or logic; spirituality, faith, and religion were considered outside these rational boundaries [17]. Empiricism focused on the idea that knowledge stems from direct, first-hand observations or sensory experiences [17]. Ultimately, these two intellectual movements challenged the authority of the church and affected the provision of general health and mental health care.

The 20th century marked a major move toward professionalism and scientific inquiry in many of the helping professions. In psychology, for example, Freud had little regard for religion and viewed it as a neurosis and an "illusion," and as behaviorism became more prominent, religion as a topic in psychology diminished [18,139,213,246]. It is not surprising that Freud wanted to distance himself from religion and specifically from Jewish traditions given the rampant hostilities and persecution against Jewish citizens during this period [246]. Freud was also influenced by the philosophies of the Enlightenment era. Behavioral theorists such as B.F. Skinner emphasized determinism and that phenomena should be measurable and observable in order to be scientific, and consequently, spirituality and religiosity were no longer considered rational explanations for health and mental health conditions [18]. It is also important to remember that spirituality was not part of the discourse during the early and mid-1900s, and religion was viewed as a direct opposition to psychology [245,246]. For the next 50 years (i.e., 1920–1970), psychology moved toward behaviorism and the cognitive sciences. Overall, there was a negative bias towards the incorporation of religion and spirituality in counseling, psychotherapy, and mental health [213].

Many supporters believe that the need to incorporate spiritual and religious attention into professional practice is based on the concept of spiritual and religious pluralism being fundamental in a multicultural society [25]. Gilligan and Furness argue that an emphasis on cultural competency means that practitioners should understand and appreciate how faith, religion, and spirituality are intertwined with the cultural values and belief systems of ethnic minority groups [26]. This is particularly important due to increased globalization and the intersection of culture and ethnic identity with other identities, such as religion, spirituality, worldviews, disability, and political affiliation [27]. In a 2019 study, counselors acknowledged the importance of considering religious and spiritual issues with clients as a core component of multiculturalism [215]. Similarly, practitioners argue that it is within a profession's ethical mandate to consider religion and spirituality because they are important factors of human experience. Not considering these issues would lead to insensitive assessment and treatment [22,243]. Furthermore, many would not argue that discussions about religion and spirituality are inevitable within certain contexts, such as bereavement, illness, and palliative care [170].

Others note that the symptoms resulting from spiritual distress are similar to the symptoms of depression [25]. Addressing potential problems of spiritual or religious origin may be an important aspect of treating depression and, potentially, other mental and health conditions. A 2016 systematic review found that higher levels of religious practice were correlated with decreased suicide ideations and attempts [171]. However, more research in this area is necessary to determine the impact of spiritual/religious interventions on overall well-being. Incorporating spirituality and religion into practice aligns with the strengths-based perspective and theories that advocate for empowering and fostering resilience [141]. In health care, it also aligns with the notion of providing patient-centered, holistic care [170,216].

Worthington and Sandage have identified several ways whereby spirituality and religion may become an issue in clinical practice [28]. First, a patient might specifically request therapy that incorporates religious components and question the practitioner's religious/spiritual background. When asked, more than 60% of clients reported agreement to the statements: "Relying on my religious/spiritual beliefs helps me to feel mentally healthy" and "My religious/spiritual help me to reach my mental health potential" [249]. Alternately, a patient might request that religion and spirituality not be discussed. If spirituality and/or religiosity are vital dimensions of a patient's life but this is not explicitly articulated, disagreements or misunderstandings may develop between the practitioner and patient regarding the course of treatment. Such a situation can ultimately hinder the practitioner from effectively treating or helping the patient. Finally, spirituality is often intertwined with culture. It is important to remember that patients are a part of a larger social system (i.e., family, neighborhood, community, religious institutions, school, employment). It is not possible to disentangle these social forces from patients' lives.

Part of scientific advancement is openness to divergent perspectives as a means to mitigate bias [217]. Avoiding discussions of religious and spiritual issues impedes science and can result in confirmation, reinforcement, and perpetuation of homogenous and potentially erroneous views.

Another challenge when measuring spirituality and religiosity stems from the varied definitions. Hill and Pargament reviewed available quantitative instruments and found that existing instruments assessed different dimensions of spirituality and religiosity [36]. Aspects of spirituality that may be addressed include [36,37,38,39,40,41,168]:

A survey found that 52% of respondents had prayed for their own health [42]. Prayer was defined as "an active process of appealing to a higher spiritual power" [42]. Overall, prayer has been identified as the most commonly used form of complementary and alternative medicine in the United States. Other techniques with spiritual or religious basis include meditation, yoga, tai chi, qigong, and Reiki [42].

There is conflicting evidence, albeit in small studies, of the positive effects of intercessory prayer, or prayer on behalf of another person, on cardiovascular health. Two studies of patients admitted to coronary care units (CCUs) examined the effects of remote, directed prayer by an outside group of Christians [49,50]. The authors of the first study found that those who were the subjects of an intercessory prayer group required less ventilatory assistance, antibiotics, and diuretics than the control group; researchers in the second study determined that those who had been recipients of prayer had significantly lower CCU course scores [49,50]. However, a study completed in 2006 found no difference in cardiac bypass patients who were recipients of intercessory prayer [135]. In fact, patients who were certain that intercessors would pray for them had a higher rate of complications compared to patients who were unsure. The authors hypothesize that there are several potential reasons for this finding differing from earlier studies: the effect was smaller than the 10% difference the study was designed to detect, the measurement (complications within 30 days of coronary artery bypass graft surgery) was not appropriate, or intercessory prayer has no effect on outcomes in patients undergoing bypass graft surgery [135].

For example, in a study with 200 cancer patients undergoing chemotherapy, those who reported higher religiosity also reported less symptom interference, lower levels of severe fatigue, and less sleep disturbance [260]. Although spirituality and religiosity should be considered as part of the assessment of cancer patients, there is not sufficient evidence to recommend participation in spiritual/religious activities as part of the treatment [65]. Addressing spiritual concerns has traditionally been regarded as an end-of-life issue, even though such concerns may arise at any time after diagnosis. The National Cancer Institute recommends that inquiries into spiritual and religious concerns be postponed for patients with cancer until after diagnosis and treatment options have been discussed and considered by the patient [43].

It has also been surmised that spirituality and religion may reduce the risk of substance misuse [78,79,80,81]. In a large-scale national study involving 17,736 adolescents, greater religiosity was protective against recreational cannabis initiation and use [184]. In another study, researchers found that positive religious coping and aspects of spirituality are protective against drinking alcohol and cannabis use [149]. Using a longitudinal design, adolescents who endorsed higher levels of religiosity were found to have lower levels of use of cigarettes, alcohol, and cannabis compared to their less religious counterparts [150]. Finally, in a systematic review of the literature from 2007 to 2013, the researchers found an inverse relationship between substance use behaviors and spirituality and religion [151]. However, it is not clear which components of spirituality and religion (i.e., commitment to substance avoidance, social support, religious involvement, or prosocial values promoted by religious affiliation) actually act as the protective factors [79]. There is also some contrary evidence that shows a positive relationship between religion and increased risk of substance misuse [79]. There is some evidence that religion is a protective factor against substance use disorder, but study results have been mixed [265].

Although there is an increasing emphasis on interventions that take a holistic approach to mental illness and working with patients and families toward recovery, some practitioners have expressed concern about focusing on spirituality and religiosity, particularly with patients who are diagnosed with severe mental and psychotic disorders [82]. Because patients with psychotic disorders may experience delusions and hallucinations with religious content, focusing on religion might exacerbate symptoms of disorganized thought and potentially promote injury to self or others [82,83,185]. Furthermore, rigid religious beliefs associated with guilt or sin may have the potential to aggravate major depression [82,146]. An extreme version of this is moral or religious scrupulosity, an obsessive concern with one's sins and moral behavior. This condition is generally considered to be a type of obsessive-compulsive disorder [84]. Scrupulosity is characterized by excessive guilt or obsession related to religious issues, often along with extreme moral or religious observance [85]. Treatment of this disorder is difficult, as practitioners often feel torn between addressing the pathology of the disorder and respecting the patient's religious beliefs. However, there is no doubt that some individuals turn to spirituality and religion in times of stress. An overwhelming number of psychiatric patients stated that religion was their source of comfort [86,87]. Religion/spirituality may be considered a mechanism of social support, positive coping and decision making, and avoidance of substance misuse. At times, it can positively impact psychological well-being [83,87]. In a small study of adults with psychosis, participants reported finding religious rituals beneficial [185]. The adults chose which religious practices in which to engage, and some identified certain scriptures that communicated autonomy and control. Interestingly, many of the participants expressed a needed to take an active role in the recovery process versus a passive approach of merely relying on God. Religion was also described as a vehicle to experience hope and purpose, which was vital in the recovery process.

A separate study of Catholic and Protestant students in Northern Ireland found that increased prayer frequency was associated with a better level of psychological health in terms of Eysenck's concept of psychoticism, which is characterized by recklessness, disregard for common sense, inappropriate emotional expression, and hostility toward authority figures [88]. Corrigan et al. found that spirituality and religiousness decreased psychiatric symptoms, increased overall management of daily tasks of life, and increased psychological well-being among those with mental illness [89]. A study conducted in Pakistan involving adults hospitalized for depression found that participants' level of religiosity predicted mental well-being [186]. A study focused on older adults found that those who had an active spiritual practice were 20% less likely to experience depression compared with those without a spiritual practice, even after controlling for socioeconomic and health variables [257]. A Canadian study of approximately 37,000 individuals found that higher worship attendance frequency was associated with a lower risk for the development of mood, anxiety, and substance use disorders [90]. In a 2012 meta-analysis of 444 studies dating back to the 1960s, 61% reported an inverse relationship between spirituality/religion and depression [146]. In another systematic review focusing on research published between 1990 and 2010 and including all types of mental disorders, 72% of the studies demonstrated an inverse relationship between religion/spirituality and mental disorders [152]. However, the findings were mixed when focusing solely on schizophrenia, and no relationship was found in studies examining only bipolar disorder. Religion may be protective against depression, but the relationship to anxiety and psychotic disorders is less clear [266].

When individuals experience health or mental health problems, spirituality or religiosity may be utilized as a form of coping. Pargament identified three ways that religion might aid individuals in coping [91]. First, religion can influence the perspective an individual assumes toward the stressor; the source of stress may be viewed as part of a divine plan or acceptance of a larger life plan [153; 243]. Second, religion can shape the coping process; that is, religion or spirituality can be employed as an inner resource to overcome the challenges associated with the health or mental health problem. Patients with mental illness often use religious or spiritual resources (e.g., prayer) to cope [229; 243]. Finally, the coping process may strengthen an individual's spiritual or religious orientation. Three different types of religious coping have been identified [91,92]:

God, Allah, and figures of a higher being are viewed as conquerors for the oppressed. Consequently, religious and spiritual orientations are often used among African Americans both to deal with and construct meaning from oppression and promote social justice and activism [96].

The belief that God is a deliverance from pain/suffering and a source of hope and salvation during times of suffering is centered on the historical legacy of slavery and its attempt to destroy African culture and families [98,268]. Many African Americans indicate that they derive their strength from the belief that God is in a personal relationship with them and that life's adversities will eventually liberate them [99]. Prayer is one religious practice through which they experience God's support, presence, grace, and affirmation, particularly during crises [189]. The Black church is often viewed as a place of community and refuge where congregants can ask for help and support [231]. Among African Americans, there is a positive relationship between spirituality and relational health, as defined by mentor and community relationships [268]. The emphasis on spiritual communalism throughout the generations remains a source of sustenance for many African Americans.

In a national survey, 83% of African Americans stated that they believed in God with certainty, and 75% indicated that religion was very important [190]. Almost half (47%) stated they attended religious services at least once a week and prayed at least daily [190]. Religious involvement has become a source of empowerment and strength for many African Americans. According to the National Survey of American Life, which included 6,082 adults in the United States, African Americans and Afro-Caribbean participants were more likely to report attendance at religious services and affiliation to a specific religious denomination than non-Hispanic White participants [5]. In many cases, African American women play critical roles in the church [98]. Emotional expressiveness often characterizes African American churches, as emotions provide a venue for suffering and sorrow [98]. The level of religiosity may correlate with older age. For example, one study found that 89% of African Americans reported being religious, but only 52% to 55% of African American adolescents indicated that religion played a very important role in their lives [155]. Overall, in many African American communities, religion represents the church, community, a place where one derives motivation, accountability, love, nurturance, and social support, and a place where practical needs (e.g., food, parenting support, counseling) can be met [252].

As noted, Judaism is the second most commonly practiced religion in the United States, following Christian denominations [1]. There are four major branches of Judaism, although smaller movements do exist worldwide. For the most part, Jewish individuals may be classified as Reform (the most liberal expression of modern Judaism); Conservative (known as Masorti Judaism outside the United States); Orthodox (the most traditional expression of modern Judaism); or Reconstructionist (the smallest and newest branch) [100,101]. Some individuals may not practice a particular religious tradition, but because of the long cultural and ethnic history, these individuals may identify either racially or ethnically as Jews [100]. Experts often refer to this as Humanistic Judaism [103].

According to the Hispanic Churches in American Life Survey, the vast majority of Hispanics/Latinos self-identified as Christians [157]. The Hispanic/Latino culture is heavily influenced by Roman Catholicism. It is estimated that Roman Catholicism plays a predominant role in the lives of approximately 90% of Hispanic/Latino Americans [107,193]. Roman Catholics strongly adhere to religious values that are centered on marriage and family, and condemnation of premarital sex, abortion, and the use of contraception is stressed [107]. In addition, the concepts of penance and redemption are key for practicing Catholics. While the main figures of Christianity are foremost (i.e., God, Jesus, and the Apostles), the Virgin Mary and canonized saints play a large role in the creation of spiritual relationships.

Spiritual histories, genograms, ecomaps, and life maps may also be useful assessment tools. A spiritual history consists of an open-ended interview that explores the patient's and his/her family's religious and spiritual beliefs, practices, and traditions. The public and private experiences of religion and spirituality are explored along a developmental life cycle [23]. Spiritual genograms are family trees that focus on religious and spiritual traditions, events, experiences, family orientation, and rituals that shape the patient's worldview and spirituality. It also provides an understanding of the individual embedded within a family system and how the family affects perspectives and practices of religion and spirituality [23,277]. A spiritual ecomap offers additional information, as it gives the practitioner an understanding of an individual's experiences of religion and spirituality within the context of the micro, meso, and macro systems levels [277]. Spiritual life maps are pictorial illustrations of the patient's spiritual journey. Like a road map, the life map indicates where the patient has come from, where the patient is now, and what the patient is moving toward [117]. When creating this map, Hodge encourages practitioners to ask patients to "highlight the trials they have encountered and the spiritual resources they have used to cope in the course of their journey" [117].

Studies show that practitioners who use spiritual interventions, such as prayer, discussing religious concepts, and forgiveness, tend to combine them with traditional therapeutic frameworks [118]. Richards and Potts highlight several practice guidelines for those considering the use of spiritual interventions [119]:

A scale to determine the suitability and the usefulness of including a spiritual adjunct to therapy has been developed. The scale ranges from appropriate to inappropriate based upon the number of principles upheld in the EBQT paradigm. An intervention is considered appropriate if the practitioner endorses all four principles. Endorsement of all four principles indicates that a spiritual adjunct might be useful and would likely be ethical given the patient's circumstances. Potential recommendations are those interventions supported by only two to three principles; the appropriateness of the action is limited to special circumstances and may not be useful for all practitioners [121]. Finally, a recommendation is inappropriate if the practitioner endorses only one or none of the principles; in these cases, a spiritual adjunct to therapy is unlikely to be useful and may not be ethical [121]. While most practitioners and researchers recognize the importance of a holistic approach that encompasses religion and spirituality, best practices for incorporation remain unclear. What specific types of interventions are most effective, under what conditions, for whom, and at what points in the therapeutic process [253]?