What countries require you to be a Muslim in order to be a citizen?

A few countries explicitly require citizenship applicants to be Muslim, primarily those governed by Islamic law. For instance, Saudi Arabia mandates that individuals must be Muslim to obtain citizenship. Similarly, in countries like Afghanistan and Iran, Islamic identity plays a significant role in citizenship eligibility. However, it's essential to note that citizenship laws can vary widely and may change, so it's advisable to consult official government resources for the most current information.