Mumma became friends with the existentialist Camus, who by then was famous for his novels The Plague and The Stranger and for essays such as The Myth of Sisyphus. The two men met to discuss questions of religious belief that Camus raised. Mumma, now 92, kept the conversations confidential for over 40 years before deciding to share them.
Soon after the following conversation on baptism, Mumma returned to the U.S. In 1960 Camus was killed in a car accident.