What's the line of thinking when Christians refuse to believe that atheists don't believe in God?

So, I’ve often encountered Christians who don’t believe me when I say I don’t believe in God. They think I’ve had some sort of spat with him and am refusing to acknowledge his presence as some sort of punishment, but deep down I know he’s there. Or something of that sort – where deep down, I know he’s there.

What’s the line of thinking for this? Religion is bullsh*t, total crap, abusive manipulation – wrong! Those are not the answers I’m looking for here. I’m looking for something along the lines of “Ah, yes, that’s John Calvin’s theory of Predestination, inspired by the humanist teachings of St. Augustine and influenced heavily by Thomas More. It’s a large part of Presbyterianism, but doesn’t usually expand beyond that denomination.” (Yes, I basically threw words out there…)