No Gods - beliefnet
The difference is quite simple when I experience anything of the Earth even something spiritual in the atheist sense of being true, or beautiful before rationalization, the fact remains that it can be rationalized and explained to others. The others may not get the same sense of spiritual wonder, but they might at least from my description understand where my spiritual experience is coming from. If I explain that I seem to be at the focal point of a brightly colored arc in the sky most people will say "Oh you mean a rainbow" It may have been a mistbow or a moonbow, but I won't quibble. They know and perhaps appreciate from having a similar experience to the one I described what I am talking about.
Similarly with almost any earthbound experience. Many more years ago than I want to admit I was 16 and in the middle of my active God search. I came out of a dark side street late evening and was stunned by the sight of the flood lighted Florence Cathedral across the plaza. Stunned in the sense I could not move or even think. All I could do was gawk at the sight. Later I could explain to my sister what I had seen, and she noted how she also was stunned even though she was expecting it and indeed looking for it.
In any experience on the Earth I can communicate what I experienced in a way that someone else could uniquely identify the experience if not the wonder I experienced. It would seem that someone experiencing God should be able to describe the experience in such a way that at least a sympathetic listener could say "Oh, that was God." It may be too much to ask for a skeptical atheist to recognize it, but at least a believer in some sort of God should recognize the description.
That was an experience when I was literally knocking on God's door, and should have experienced God if God existed. That and similar experiences where I was actually presupposing God not No-God, and got no result.