Religious education teaches the doctrines of a religion. Its usual purpose is to indoctrinate children in the religious beliefs of their guardians. A less common purpose is to indoctrinate new adherents of a religion.

Since all people hold different religious beliefs, government-sponsored religious education is a source of conflict. Countries vary widely in whether religious education is allowed in public schools. Those that allow it also vary in the type of education provided.

People who oppose religious education in public schools believe that if religion is taught in school, some children will be excluded because they do not belong to a mainstream religion or any religion at all. They suggest that teaching religion in schools seems to value one religion over another and may make people of other religions feel uncomfortable or pressured to believe what the school teaches. Proponents of school religious education argue that religious beliefs have historically socialized people's behavior and morality. They feel that teaching religion in school is necessary to encourage children to be responsible, spiritually sound adults.

In the United States, religious education is usually a supplementary "Sunday school" taught to children while their parents attend church. Jews, Muslims, Christian and people of other religions may send their children to special classes at a place of worship after public school. Some families believe supplementary religious education is inadequate, and send their children to private religious schools. Most faiths have college and graduate-level religious schools, but they are private. Many religious schools provide excellent, inexpensive education, sometimes superior to government schools. Religious education is forbidden in public schools, unless all religions are treated as equally valid. There is a strong tradition of public tolerance of individual religious choices, as the US Constitution establishes in the First Amendment of its Bill of Rights. Schools may teach about religions in an academic way, but endorsing one religion is illegal. Nevertheless, students are expected to say the Pledge of Allegiance, which describes the U.S. as "one nation under God." The reference to God was added in 1954 after the Knights of Columbus campaigned for its inclusion. The 'Newdon v. California' decision in 2002 was successful in challenging this phrase.

Most European countries and some of their former colonies maintain a state-supported religion, usually either Lutheran or Roman Catholic. It is taught in a special class of the government schools. This policy aims to build and maintain a national identity. In many countries families can get permission to withdraw children from these classes. Many families with other religions use religious schools. The state supports one (usually) central seminary which trains pastoral staff for the state church. Other religions may support private seminaries, but these are small and poorly funded. Religions other than the state religion, even if ancient and respectable, are often deprecated in the national cultures (e.g. they are called "cults" in the news media).

In France, the state recognizes no religion and does not fund religious education. However, the state subsidizes private teaching establishments, including religious ones, under strict conditions of not forcing religion courses on students and not discriminating against students according to religion. An exception is the area of Alsace-Moselle where, for historical reasons, the state supports public education in some religions.

In traditional Islamic education, children are taught to read and sometimes speak Arabic and memorize the major suras of the Koran. Many countries have state-run schools for this purpose. Traditionally, a settlement may pay a mullah to teach children. In many Islamic cultures, education for women is thought unnecessary, although in all Islamic cultures, families often work hard to afford schools for their daughters. There is a historic tradition of clever Sufi mullahs who wander and teach amusingly, and an ancient tradition of religious universities. Religious scholars often serve as judges, especially for criminal and family law (more rarely for commercial law). Non-Islamic religions are tolerated as personal beliefs, but not as public teaching. Most Islamic countries have laws against teaching other religions, and especially against attempts to convert Islamic believers.

Similarly, children receiving a traditional Jewish education are often taught some Hebrew, and students at Greek Orthodox schools typically learn some Greek. These traditions generally hope that by passing on the traditional language, the students will also retain a better memory of their culture's history and a stronger sense of cultural identity.

In the People's Republic of China, religious education is banned except in licensed schools of theology, which are usually college-level and above. These colleges are state-supported and usually very small, with limited enrollments and budgets. Religious education usually occurs in scheduled sessions in private homes. Religious teachers usually move on a weekly or monthly circuit, staying as guests in private houses in exchange for teaching.

In Thailand, Burma and other majority Buddhist societies, Buddhist beliefs are taught in school, often by monks. Young men are expected to become monks for several years.

In Japan, Buddhism, Confucianism, and Shinto coexist. Religious instruction normally occurs in temples as a part-time voluntary activity, reinforced by public ceremonies and parades.