Mathematician.

Paul Erdős (26 March 1913 – 20 September 1996) was a Hungarian mathematician. Erdős published more papers than any other mathematician in history, working with hundreds of collaborators. He worked on problems in combinatorics, graph theory, number theory, classical analysis, approximation theory, set theory, and probability theory.

Sources:

1.) Vithal C Nadkarni (Apr 28, 2011). "Are Facts Sacred?". The Economics Times. Retrieved 6 June 2012. "The Hungarian mathematician Paul Erdos was a confirmed bachelor and atheist."

2.) Varadaraja Raman (2005). Variety in Religion And Science: Daily Reflections. iUniverse. p. 256. ISBN 9780595358403. "Erdös had a pungent wit. As an atheist who had suffered under fascist regimes, he described God as a Supreme Fascist."

3.) Nathalie Sinclair, William Higginson, ed. (2006). Mathematics and the Aesthetic: New Approaches to an Ancient Affinity. Springer. p. 36. ISBN 9780387305264. "Erdös, an atheist, named 'the Book' the place where God keeps aesthetically perfect proofs."