This is an article about culture and religion. First, I discuss how social psychologists usually teach culture in their Social Psychology classes, focusing on east-west differences in individualism and collectivism. Then I propose that religious groups are cultures, because they have all of the defining features of cultures (such as beliefs and values). I then describe some studies I have done on moral judgment differences across religious cultures. If a married man thinks about having an affair, Christians consider this adultery, and Jews do not. Through mediation analyses and multiple experiments, I show this is because of differences between Jewish and Christian theology – specifically, that Christians agree more than Jews do that thoughts are as morally important as actions. Similar effects show up for a person who does not like his parents (but acts as though he does), and for a person thinking about poisoning a professor’s dog to retaliate for a bad grade. Last, I talk about why this work matters for understanding culture. I propose that religions shape cultures, that results like these can help us understand cultural universals and culturally specific beliefs and practices, and I consider how religion relates to other forms of cultural differences (like east-west differences in individualism and collectivism).