This study examined the relation between religious faith and gratitude variables with the severity of mental disorders symptoms. Participants were 300 students of Shiraz University who were selected via cluster random sampling method. Measures were Islamic – Iranian Gratitude, Religious Faith, and SCL-90 questionnaires. The data were analyzed using descriptive and multiple regression methods. The results showed that almost all gratitude and faith subscales could predict the severity of all mental disorders subscales of the SCL-90. Faith and gratitude had a broad effect on interpersonal sensitivity and depression subscales. Internal gratitude predicted the severity of all mental disorders and among religious faith subscales, purposefulness, goodwill and self-control predicted the severity of some mental disorders symptoms greater and broader than other subscales. Religious faith and gratitude may be considered as general factors which are effective in reducing a wide range of mental disorders symptoms. Results indicate that if being religious causes inter­nal changes and develops internal gratitude, purposefulness, goodwill and self-control in an individual, it would prevent mental disorders.