Substance abuse by young people remains one of the most widespread and costly problems in Europe. Some previous studies reported an association between sexual orientation and substance use whereas it is assumed that religiosity could be a protective factor regarding substance use.

To better understand the relationship between substance use, sexual orientation and religious beliefs.

The C>SURF study concerns Swiss male adults who have to go through the mandatory recruitment process at the army. Data were collected between August 2010 and November 2011. A questionnaire about the participants’ socio-professional and family background, their consumption of alcohol, cannabis and other drugs, as well as their personality was sent to be filled in online. The final sample included 5990 males between 17.9 and 31.4 years old (mean=20.01, sd=1.24). 77% of subjects declared belonging to a religious community whereas 29% said they are atheists. 91% described themselves as being exclusively attracted by females, 8% by males and females and 1.0% by males only.

Belonging to a religious community or declaring not being atheist seems to be a protective factor regarding any substance use. Heterosexual men declare most often belonging to a religious community but they do not differ regarding being atheist. Logistic regression on predicting the belonging to a religious community additionally shows a significant interaction between cannabis use and being gay.

There are significant associations between substance use, sexual orientation and religious beliefs and a better understanding of these relations would lead to a relevant clinical impact.