I recently got into a discussion with a Calvinist friend of mine as to whether it is possible that an atheist, deep down in his heart, could actually believe that God does not exist. He said that every atheist actually does believe in God, deep down, and he pointed out a scripture passage (I forget the reference) which basically said that those who don’t believe in God are without excuse for their unbelief. I agreed that they are without excuse, as God has revealed his existence in many ways to all (General revelation: Nature, etc.), but I also pointed out that this is not that same issue as truly believing whether God exists or not. The passage deals with culpability, not knowledge alone. Example: An 11th grader could be illiterate and have no excuse for being so,(i.e. he’s at fault for it) but it doesn’t change the fact that he’s still illiterate. I argued that an atheist could actually honestly not believe. I thought that what my friend was saying was a Calvinist thing, but I’m not 100% sure. So my question is: what does the Catholic Church teach on this? Could an Atheist have deluded himself to a point at which he honestly, in his heart, believes that there is no God? Or does every atheist really know that God exists and is just rebelling against Him?
Thank you in advance for your replies.