Ignace Lepp (born John Robert Lepp; 26 October 1909 Orajõe, Pärnu County, Livonia, Russian Empire – 29 May 1966 near Paris, France), was a French writer of Estonian origin. According to his book Atheism in Our Time, Lepp was an atheist and Marxist for many years and claimed to have occupied important positions in the communist party with whom he later became very disillusioned. He then converted to Roman Catholicism and was ordained a priest in 1941. He wrote many non-fiction books including some about atheism, religion, and later psychiatry, as he was a psychologist and psychoanalyst.He wrote among other books: The Ways of Friendship, The Psychology of Loving, The Authentic Existence, The Communication of Existences. He also wrote The faith of men; meditations inspired by Teilhard de Chardin (Teilhard et la foi des homme), about the French thinker Pierre Teilhard de Chardin.