Rudolf Carnap (May 18, 1891 – September 14, 1970) was an influential German-born philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism.
1.) R. Carnap: Intellectual Autobiography. in: P. A. Schilpp (editor): The Philosophy of Rudolf Carnap. Cambridge University Press, La Salle (Illinois) 1963.
2.) Martin Gardner said "Carnap was an atheist..." A Mind at Play: An Interview with Martin Gardner, by Kendrick Frazier, Skeptical Inquirer, March/April 1998 (Accessed July 2, 2007).
3.) "Carnap had a modest but deeply religious family background, which might explain why, although he later became an atheist, he maintained a respectful and tolerant attitude in matters of faith throughout his life." Buldt, Bernd: "Carnap, Paul Rudolf", Complete Dictionary of Scientific Biography Vol. 20 p.43. Detroit: Charles Scribner's Sons, 2008.