In religion and theology, revelation is the revealing or disclosing of some form of truth or knowledge through communication with a deity or other supernatural entity or entities.

Some religions have religious texts which they view as divinely or supernaturally revealed or inspired. For instance, Orthodox Jews believe that the Torah was received from Yahweh on biblical Mount Sinai, and Muslims believe the Quran to have been revealed to Mohammed word by word and letter by letter. In Hinduism, some Vedas are considered apauruṣeya, i.e. "not human compositions", and are supposed to have been directly revealed, and thus are called śruti, i.e. "what is heard". Many Christians believe that the Old and New Testaments were inspired by God. The 15,000 handwritten pages produced by the mystic Maria Valtorta were represented as direct dictations from Jesus, while she attributed The Book of Azariah to her guardian angel. The Book of the Law, written by Aleister Crowley, was said by him to have been revealed by three successive Egyptian deities.

When a revelation is communicated by a supernatural entity that is reported as present during the communication, it is called a vision. Some revelations go further in that direct conversations between the recipient and the supernatural entity is reported. Some revelations are reported along with physical marks such as stigmata and in rare cases, such as that of Saint Juan Diego, physical artifacts accompany the revelation. The Roman Catholic concept of interior locution includes just an inner voice heard by the recipient.

In the Abrahamic religions, the term is used to refer to the process by which God reveals knowledge of himself, his will, and his divine providence, to the world of human beings. Revelation from a supernatural source is of lesser importance in some other religious traditions, such as Taoism and Confucianism. In secondary usage, it refers to the resulting human knowledge about God, prophecy, and other divine things.