One effort to characterize individuals by types of spiritual and religious experience  identified the following three groups, using cluster analytic techniques:
- Religious individuals who highly value religious faith, spiritual well-being, and the meaning of life.
- Existential individuals who highly value spiritual well-being but not religious faith.
- Nonspiritual individuals who have little value for religiousness, spirituality, or a sense of the meaning of life.
Individuals in the third group were far more distressed about their illness and were experiencing worse adjustment. There is as yet no consensus on the number or types of underlying dimensions of spirituality or religious engagement.
From the prospective of both the research and clinical literature on the relationships between religion, spirituality, and health, it is important to consider how these concepts are defined and used by investigators and authors. Much of the epidemiological literature that has indicated a relationship between religion and health has been based on definitions of religious involvement such as membership in a religious group or frequency of church attendance. Somewhat more complex is assessing specific beliefs or religious practices such as belief in God, frequency of prayer, or reading religious material. Individuals may engage in such practices or believe in God without necessarily attending church services. Terminology also carries certain connotations; the term religiosity, for example, has a history of implying fervor and perhaps undue investment in particular religious practices or beliefs. Religiousness may be a more neutral way to refer to the dimension of religious practice.
Spirituality and spiritual well-being are more challenging to define. Some definitions limit spirituality to mean profound mystical experiences; however, in considerations of effects on health and psychological well-being, the more helpful definitions focus on accessible feelings, such as a sense of inner peace, existential meaning, and purpose in life, or awe when walking in nature. For the purposes of this discussion, it is assumed that there is a continuum of meaningful spiritual experiences, from the common and accessible to the extraordinary and transformative. Both type and intensity of experience may vary. Other aspects of spirituality that have been identified by those working with medical patients include a sense of meaning and peace, a sense of faith, and a sense of connectedness to others or to God. Low levels of these experiences may be associated with poorer coping (refer to the Relation of Religion and Spirituality to Adjustment, Quality of Life, and Health Indices section).