Many studies have examined the influence on sexual attitudes and behavior of religious belief (i.e., religious denomination) or religiosity (e.g., attendance at services, subjective importance of religion). However, few studies have examined the combined effects of religion and religiosity on sexual attitudes and behavior. This study examined such effects in a representative sample of 19,307 Australians aged 16-59 years (response rate, 73.1%). The study compared members of four religious groups (Protestant, Catholic, Buddhist, Muslim) and two levels of frequency of attendance at religious service (less than monthly, at least monthly). Religious participants were compared to their non-religious peers in analyses adjusted for potential confounding by demographic variables. The outcomes were five sexual behaviors and five corresponding measures of sexual attitudes. The study revealed inconsistent patterns of association between religion/religiosity and a range of sexual behaviors and attitudes. In general, greater attendance at religious services was associated with more conservative patterns of behavior and attitudes. However, religious people who attended services infrequently were more similar to their non-religious peers than their more religious peers. The results of this study highlight the importance of considering not only religion or religiosity, but the intersection between these two variables.