The Ninth Configuration (1980) Truth in plain sight

Captain Cutshaw, is a Vietnam war enlistee, militantly atheist and a NASA astronaut who aborted a moon launch and was dragged screaming from the capsule, suffering from an apparent mental breakdown.

Col. Vincent Kane, a U.S. Marines psychiatrist repeatedly ask Captain Cutshaw about him why he did not want to go to the moon, but he refuses to answer. Then Vincent and Cutshaw debate about the existence of God where Vincent explains why the existence of a God is far more likely than life having emerged by random chance.