This study examines the relationships among religiosity, affiliation with Islam, and attitudes toward wife beating. A series of individual-and country-level mixed modeling is performed on a sample of 45,268 subjects in 37 countries. The sample is derived from the World Values Survey. The results show that affiliation with Islam is related to an accepting attitude toward wife beating regardless of demographics; a Muslim's attitude toward gender inequality; or the country's aggregated gender inequality, predominant religion, human development level, and religious diversity. However, a Muslim who maintains a high-level belief religiosity exhibits a less accepting attitude toward wife beating than a Muslim who has a low-level of belief religiosity. Furthermore, a Muslim who lives in a country with a high level of nationally aggregated belief religiosity is likely to have a low acceptance of wife beating. However, individual religious service attendance fails to correspond significantly with individual attitudes toward wife beating. These findings suggest that Muslims' high level of acceptance toward wife beating is not fully explained by their high level of belief religiosity, ritual religiosity, or personal attitude toward gender inequality. In addition, increasing the belief religiosity among Muslims may contribute to decreasing their acceptance of wife beating.