Reincarnation is the philosophical or religious concept that the non-physical essence of a living being starts a new life in a different physical form or body after biological death. It is also called rebirth or transmigration, and is a part of the Saṃsāra doctrine of cyclic existence. Saṃsāra is the cycle of death and rebirth.

Reincarnation is a central tenet of Indian religions, namely Jainism, Buddhism, Sikhism and Hinduism, although there are Hindu groups that do not believe in reincarnation but believe in an afterlife. A belief in rebirth/metempsychosis was held by Greek historic figures, such as Pythagoras, Socrates, and Plato. It is also a common belief of various ancient and modern religions such as Spiritism, Theosophy, Anthroposophy and Eckankar and as an esoteric belief in many streams of Orthodox Judaism.

Although the majority of denominations within Christianity and Islam do not believe that individuals reincarnate, particular groups within these religions do refer to reincarnation; these groups include the mainstream historical and contemporary followers of Cathars, Alawites, the Druze, and the Rosicrucians.

The historical relations between these sects and the beliefs about reincarnation that were characteristic of Neoplatonism, Orphism, Hermeticism, Manicheanism, and Gnosticism of the Roman era as well as the Indian religions have been the subject of recent scholarly research. Unity Church and its founder Charles Fillmore teaches reincarnation.

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