Modern philosophy was founded by Rene Descartes, who was a scientist and mathematician. It was he who insisted that philosophy should be no more and no less than a science. But Descartes was also a good Catholic, who had no intention of opposing the Church; he therefore kept his philosophy and his religion in different compartments. He accepted that only the Church can provide the answers to questions about the meaning of human existence and human freedom. The mainstream of philosophy accepted the Cartesian tradition that philosophy and religion should be kept in separate compartments. Existentialists do not accept the view that philosophy has no right to ask ‘religious’ questions. This is not to say that they reject Descartes’ idea that philosophy should be a science. The chapter outlines a new form of existentialism that avoids this cul de sac, and that can continue to develop.