Background. Negative associations between religion and suicide, in individuals and countries, may be mediated by the degree to which suicide is tolerated.

Methods. Linear regression was used to examine ecological associations between suicide tolerance, religion and suicide rates in 19 Western countries in 1989/90. Logistic regression was used to study associations between suicide tolerance and strength of religious belief in 28085 individuals in these countries. The concept of effect modifying function was used to examine whether the strength of the association between suicide tolerance and religious belief in individuals depended on the extent of religious belief in their country.

Results. Higher female suicide rates were associated with lower aggregate levels of religious belief and, less strongly, religious attendance. These associations were mostly attributable to the association between higher tolerance of suicide and higher suicide rates. In the 28085 subjects suicide tolerance and the strength of religious belief were negatively associated even after adjustment for other religious and sociodemographic variables and general tolerance levels (odds ratios: men 0·74 (95% CI 0·58–0·94), women 0·72 (95% CI 0·60–0·86)). This negative individual-level association was more pronounced in more highly religious countries but this modifying effect of the religious context was apparent for men only.

Conclusions. Ecological associations between religious variables and suicide rates are stronger for women than men, stronger for measures of belief than observance and mediated by tolerance of suicide. In individuals, stronger religious beliefs are associated with lower tolerance of suicide. Personal religious beliefs and, for men, exposure to a religious environment, may protect against suicide by reducing its acceptability.