Oliver Stone describes himself as a practicing Buddhist. Specifically, he has said he follows the Tibetan branch of Buddhism. He was not born into Buddhism, but adopted the faith as an adult.
Oliver Stone's father was a Jewish American stock broker. His mother was a French Catholic. Neither of Stone's parents were particularly religious. In fact, they raised him in neither Judaism nor Catholicism. Stone was raised as an Episcopalian, and regularly attended Episcopalian church services and Sunday School as a youth. He thought of himself as a Protestant, but describes himself as not particularly religious while growing up.