Religion is a diversity factor that comprises a significant component of identity for many clients. However, little attention has been paid to religion in the context of group counseling, especially process-oriented, nonthemed groups with heterogeneous membership. Using multicultural, process-oriented, and social justice theories of groups, we demonstrate the myriad ways religion is relevant to and influential in group counseling work. Together, these theories provide a solid justification for the need to ethically and effectively attend to religion in group work. Furthermore, they provide a strong foundation for developing counseling expertise in this area by highlighting typical conflicts, group dynamics, and needs that arise when religion is addressed in groups. Based on our review, we provide practical and ethical implications to assist group leaders in addressing religion in their group counseling work.