The prejudices theists’ hold against atheist stems from the perception that atheists’ lack a source of moral guidance normally provided by religious belief. Since theists perceive atheists as morally lacking, influencing perceptions of atheists as morally similar to theists should bolster positive attitudes towards atheists, and limit prejudice. However, increased moral similarity should be threatening to theists’ religious social identity, and may lead to theists’ expressing prejudice against atheists. Indeed, in Study 1 (N = 62), prejudice against atheists occurs when highly religious people perceive atheists as sharing their religious group’s morality. This relationship was a function of theists’ fear for the religious group’s future (collective angst). In Study 2 (N = 145), the effect of moral similarity (versus moral difference) on collective angst and prejudice against atheists was experimentally tested and but did not support the results of Study 1. Implications of these models will be discussed.