I actually enjoy religious debate to a point (until it becomes circular).

Responses I’ve got usually settle on the fact my outlook and actions follow Jesus’s teachings, and that because I have morals – and god is the originator of morals – I clearly do follow god, even if I don’t want to admit it to myself.

Trying to tell people that ethics didn’t originate with their bible, and that obviously people had morals tens of thousands of years before Christianity even existed (because otherwise cooperative societies would not have formed) is something they can’t even fathom, it’s so far outside their worldview.

Some insist I must believe in god in order to reject him, and can’t understand when I point out they don’t have to believe in leprechauns in order to reject them.

For indoctrinated and devout Christians, there doesn’t seem to be a way to break through the fog. I’ve two friends who will begin shouting at me over this, though they’re perfectly reasonable the rest of the time. Years of this is exhausting, as you say, so now I’ve mostly stopped trying.