Objective: The associations between religiousness, authoritarianism, and religious fundamentalism and anti-gay/lesbian (GL) attitudes were examined as well as the possible mediating function of religious fundamentalism on the religiousness–anti-GL attitude relation. Method: A sample of 249 Jewish Israeli undergraduate students participated in an online survey and filled out self-report measures of religiousness (religious behavior and belief), intratextual religious fundamentalism, right-wing authoritarianism, and anti-GL attitudes. Results: Religiousness, authoritarianism, and religious fundamentalism were all positively and significantly associated with anti-GL attitudes (rs = .69–.79). Hierarchical regression analysis indicated that religious fundamentalism had a unique contribution to the prediction of these attitudes even after controlling for religiousness and authoritarianism. Respondent gender and target gender did not moderate these relations. Finally, a mediation analysis using boot-strapping methodology indicated that religious fundamentalism and authoritarianism each mediated the religiousness–anti-GL attitude relation, and multimediation analysis showed that religious fundamentalism and authoritarianism together mediated this relation and that each variable had a unique and significant contribution to the mediating function. Conclusions: There are two paths between religiousness and anti-GL attitudes where one path—religious fundamentalism—is inherently religious and the other—authoritarianism—is not. It may be more profitable to attenuate anti-GL attitudes, that are associated with anti-GL violence, via the nonreligious path. (PsycINFO Database Record (c) 2018 APA, all rights reserved)