It's pretty simple it is the rejection of ALL revealed religion and through nature we can observe that the universe MUST have a creator, the universe is mathematically complext.Even the human body contributes to this fact. furthermore, mistakes are not "sins", they will bond to accure and mistakes are just a product of our existance, in other words we learn from our mistakes. Our moral codes are older than the bible itself. Moral laws of conduct date back to the early sumer settlements near what is known as present day Iraq.These areas which are highly influence with "revealed religion" have NEVER seen unrest.Revealed religion has never been able to contribute to peace due to there thinking "My holy text is the only way", this is what has caused many of the crusades and other supposed holy wars.