A confessional state is a state which officially practices a particular religion, and at least encourages its citizens to do likewise.
Over human history, many states have been confessional states. This is especially true in countries where Christianity, Islam and Buddhism were the religions of the state. The idea of religious pluralism in modern terms is relatively recent, and until the beginning of the 20th century, many if not most nations had state religions enshrined in their respective constitutions or by decree of the monarch, even if other religions were permitted to practice.
However, there are many examples of large multicultural empires that have existed throughout time where the religion of the state was not imposed on subjected regions. For instance, the Mongol Empire, where Tengrism was the religion of the court, but not imposed on those ruled by the Mongols, the Achaemenid Empire and the Roman Empire before Constantine I, where regional clergies and practices were allowed to dominate as long as offerings were made to Roman Gods and tribute paid to Rome.
Religious minorities are accorded differing degrees of tolerance under confessional states; adherents may or may not have a set of legal rights, and these rights may not be accessible in practice. For example, in medieval Europe Jewish people suffered various degrees of official and unofficial discrimination; during the same period in Islamic states, non-Muslims or dhimmi were legally inferior to Muslims but accorded certain protections.