Two things you should consider
1. Your belief cannot change reality. For example: A person can believe and say there is no heaven, but if one exists, their saying it does not make heaven cease to exist. It is obvious to the sensibilities that are common to man, that there is such a thing as truth, and that believing otherwise does not negate the truth.
2. If you are "believing" in something you don't hold to be absolutely true, why bother?
When someone thinks about daily, practical things in a way that denies the evidence around them, we call it delusional and consider them mentally ill. Why apply such illogical thinking to the spiritual realm? Regardless of the modern terms applied to such thinking "progressive", "tolerant", "post-modern" or any other politically correct term...