Religious people do understand
Written as a response to Christians just don't seem to understand.
Sigh, man. I feel you.
You are a smart individual, but I think you need to realize that when you tell a religious person "God does not exist" or anything remotely even close to that, what they actually hear is "Your mom and dad and other assorted abusers are bad people who systematically lied to you". So you should not be surprised when he comes back at you with the equivalent of "My dad can beat you up!" ("God is great and he will punish you").
Do you not find it at least somewhat surprising that he regresses to this childlike state and attacks you? Do you not see the parallels between his defensiveness and the defensiveness of an abuse victim who denies that he has been abused?
When you speak of religion to a religious person, you are not speaking to him -- you are speaking to his early childhood traumas. Reason does not work because the religious person has learned to systematically shut it off as a coping mechanism for the abuse he endured. They've just been -- consciously or otherwise -- incapacitated by their abusers (generally parents, schoolteachers, other authority figures) so they can't see the abuse. And, by trying to talk about this abuse to these victims, all you're bringing up is the negative feelings and having them associated with *you*.
This is all well-documented in The Bomb in the Brain series that you can watch on YouTube.
Christians understand. Oh, believe me, they do, they know full well that you are right. They just won't accept it, because acceptance of reality -- and the itinerant chain of realizations and consequences that follow from said acceptance -- would just be too painful to deal with. They hate you because you're right.