Why have evangelical Christians resisted public-health warnings about COVID-19? Christianity upholds the ethical principle of reciprocity: doing unto others as you would have the do unto you, and not wearing masks violates that principle, since they do not just protect the people wearing them, but also others who might catch the coronavirus and potentially die from it. The answer to the question may lie with the unholy alliance that has emerged in the U.S. between some conservative Protestants and conservative politicians, infusing religion into our politics and dismissing science by blind-faith followers of a bad-faith president.