IMO , it is not a case of there being no evidence either way as to the existence of a Devine being. The fact is there is a creation that got here somehow.   Very few opt for an eternal universe , I understand, so that either means it was created, or it sprung out of nothing. Then it boils down to presuppositions adopted by each position. To the theist, it is obvious that the universe could not come into existence without intelligence and great power. The atheist is obviously not satisfied with that logic and demands other evidence.                               The " irrational belief" , IMO ,as Steve says, and suggests is applicable to the theist, is rather more apt for the atheist.