Abstract: When, if ever, is it legitimate for law to ban sex discrimination by religious institutions? It is best to approach this question by noticing that most of the time, ordinary civil and criminal law are legitimately applied to such institutions. For example, members of religious organizations cannot commit torts, even if the commission of torts is said to be part of their religious practices. Many people seem to accept what might be called an Asymmetry Thesis, which holds that sex equality principles may not be applied to religious institutions, whereas ordinary civil and criminal law may indeed be applied to them. This essay argues that the Asymmetry Thesis cannot be defended, and that much of the time, sex equality principles are properly applied to religious institutions. Discussion is also devoted to the controversial idea that facially neutral laws may be applied to religious institutions even if they have a severe adverse effect on religious practices.