In an earlier article we reviewed the latest research on the relationship between religious involvement and mental health, the effects of religiosity on mental health and well-being over time and the impact of religious interventions. Here we focus on clinical applications that may be useful to psychiatrists and other mental health professionals. We discuss general clinical applications relevant to all patients (e.g. taking a spiritual history, supporting/encouraging religious beliefs, referring to clergy), violations of clinician–patient boundaries and the need to ensure that religious/spiritual interventions are patient-centred. We describe evidence-based religious interventions and how to identify appropriate patients for this approach. Finally, we explore situations in which religious beliefs and practices may be a problem, not a resource, and make recommendations on how to address such cases. Case vignettes illustrate clinical situations that mental health professionals are likely to encounter. Although the focus is on the North American context, we note how practice and culture in the UK may differ.