Jean-Paul Sartre was an influential French existentialist philosopher, dramatist, novelist and critic. His religious beliefs and influences varied over the course of his life. He was a Luthean, Freudian, Marxist and a militant atheist. Toward the end of this life he embraced messianic Judaism.
For further details about Jean-Paul Sartre's religious beliefs, see: Tihomir Dimitrov, "Jean-Paul Sartre" (Part II: Chapter 34) in 50 Nobel Laureates and Other Great Scientists Who Believe in God (2007), (http://nobelists.net/; viewed 19 April 2007).