After diagnosis of cancer, many patients show more inclination towards religion and religious activities. This qualitative study using semi-structured interviews explored the perspectives and experiences of 17 Iranian cancer patients and their families regarding the role of religion in their adaptation to cancer in one of the hospitals in Tehran and a charity institute. The content analysis identified two themes: "religious beliefs "(illness as God's will, being cured by God's will, belief in God's supportiveness, having faith in God as a relieving factor, and hope in divine healing) and "relationship with God during the illness." In general, relationship with God and religious beliefs had a positive effect on the patients adapting to their condition, without negative consequences such as stopping their treatment process and just waiting to be cured by God. Thus a strengthening of such beliefs, as a coping factor, could be recommended through religious counseling.