Most assume that when governments support a religion, they do so in the hope that they will increase their legitimacy. However, a growing literature implies that support for religion may decrease a government’s legitimacy for three reasons. First, political secularism, an ideology mandating the separation of religion and state or state restrictions on religion, is increasingly popular. Second, state support for religion can undermine religious vitality. Third, support for religion entails an element of government control over religion which can undermine the perceived authenticity of a religion. We test this support–legitimacy relationship in Christian-majority countries from 1990 to 2014 using the Religion and State and World Values Survey data, comprising 54 countries and 126 country years. We find that state support for religion is associated with lower levels of individual confidence in government. We posit this has important implications for our understanding of the underpinnings of legitimacy.