Quora: What makes atheists so sure that gods don't exist?

We are only sure (99%) that the theistic gods of fundamentalist religions don't exist, because they've been directly refuted by empirical evidence and there is no evidence to support them. Beyond that, there's any number of abstract concepts you can call a "God" to be evasively vague. First define what you mean by God, and then we can argue. The narrower your definition, the more specific the evidence required to refute it. Is there "something" out there that looks out for our species in some way? Maybe. Is there "something" out there that guided our evolution? Maybe. If you'll put it that way, every atheist will admit that these are possibilities — but they don't give you grounds for any further assumptions