In France, Khalil discovered Sartre's philosophy and was “deceived by it and by existentialism,” until he read Sartre’s book "Reflections on the Jewish Question." The book acted as a declaration of support for Israel, which made Khalil feel betrayed. He wondered why Arabs translated his works and was surprised by Sartre’s dualism, as he supported the Algerian Revolution and had advocated for peoples’ rights but apparently also supported the colonization of Palestine. He later discovered that the book was in fact a response to Marx’s book "On the Jewish Question". Around that time, Khalil published his book Sartrism: The Paradox of Politics and Ethics (original: "Ālsārtryā wthāft ālsyāsā walāẖlāq").