"Were it not for the existence of sin in the world, says Calvin, human beings would believe in God to the same degree and with the same natural spontaneity displayed in our belief in the existence of other persons, or an external world, or the past. This is the natural human condition; it is because of our...
presently unnatural sinful condition---that many of us find belief in God difficult or absurd. The fact is, Calvin thinks, one who does not believe in God is in an epistemically defective position-rather like someone who does not believe that his wife exists, or thinks that she is a cleverly constructed robot that has no thoughts, feelings, or consciousness."
...evolution/sin sickness!
one who does not believe in God is in an epistemically defective positionA yes/no belief in god is a false dichotomy. The question would be far more honestly framed by asking whether or not a person believes in an identical God as someone else. Of course, in all cases, for all people, the answer would be "No." "God" is a personal construct, for each individual to define and worship-- or not-- as they see fit.
Regardless of the above, however, the existence or not of a god has no effect on observation, prediction, and attempted falsification-- the process of normal science in any discipline.