The present research focuses on negative stereotypes about religious believers (e.g., Christians) and non-believers (atheists), and the behavioral consequences of these stereotypes. In the first part of my talk, I will show that stereotypes about Christians being less competent in science are pervasively recognized by both Christians and non-Christians, as well as openly endorsed by non-Christians. Awareness of these stereotypes in turn causes Christians to underperform in scientific domains and disidentify with science in general. Using different manipulations of stereotype awareness and different measures of scientific performance, my studies demonstrate that Christians perform less well on scientific tasks and identify less with science than do non-Christians when negative stereotypes of their group are made salient, but exhibit equivalent science performance and identification when the stereotypes are explicitly removed. In the second part of my talk, I will present studies suggesting that atheists can also be vulnerable to negative stereotypes about their ingroup. Specifically, given the widespread societal stereotypes of atheists as amoral and untrustworthy, atheists (but not Christians) behave more altruistically in a trust game when paired with an outgroup [Christian] than ingroup [atheist] partner, especially when reputational concerns are salient. Implications of these results for the underrepresentation of Christians in scientific fields, the conditions under which negative stereotypes of Atheists are perpetuated versus disconfirmed, and interpersonal interactions between religious believers and non-believers will be addressed.