Which individual described religion as the feelings, acts, and experiences of individual men in their solitude?

The description of religion as encompassing the feelings, acts, and experiences of individuals in their solitude is attributed to William James, a prominent philosopher and psychologist. James emphasized the subjective nature of religious experience, highlighting how personal and often solitary encounters shape one's understanding of religion.

His work, particularly in "The Varieties of Religious Experience," focuses on the personal, psychological aspects of faith and how individual experiences contribute to broader definitions of religion. He believed that the essence of religion lies not in institution or dogma, but rather in personal experiences and feelings that individuals have, especially in moments of solitude.

In contrast, the other philosophers mentioned have different perspectives on religion. Émile Durkheim, for instance, focused on the social functions of religion and its role in maintaining social order, while Paul Tillich and Sigmund Freud examined religion through existential and psychological lenses, respectively, but did not specifically emphasize the solitary individual experience as the core definition of religion. James’s unique focus on individual experience makes his viewpoint distinct and aligns perfectly with the description in the question.