Well I like to show that not only have I read the bible, but deeply investigated it. This helps dispel the myth that if we just understood we would believe. I show them that I understand even better, and that lowers that a bit. Of course, believers are prone to confirmation bias, so it is possible that no matter what I say, they will conclude that I did not search.
For instance, I can prove that I have done a thorough study of the bible that goes deeper than anything they have done, but they will conclude that I did not open my heart. Then I'll tell them that I was a believer when I embarked on this endeavor and had a wide open heart, and they may conclude that I didn't have my heart in the proper place even if it was open. Then I tell them the long list of religions I researched, attended, studied with, and they conclude but I just hadn't found the RIGHT one, which is always their brand. Or they tell me I rely on the bible too much, and that this information should come through private revealtion. So I tell them I used to pray in earnest and tell God that whereever he led me, whatever the answer, I would listen and respond.
And it goes on and on and on. I think it is very difficult for them to accept that someone could have unshakeable faith, just like theirs, and deeply felt the presence of God, and one day concluded that he was not there. That's pretty scary for them. So they much conclude that there was some flaw in my faith, something THEY don't have, of course. Or that I felt hurt or angry---quite the contrary. I felt no such things at the time I came to this conclusion. I simply could not deny the facts anymore. My brain would not allow it.
Ah well. I know as a believer I was incapable of understanding the atheist viewpoint no matter how much I thought I did. But having been a believer for most of my life, and attending many different churches, I do understand what it means to be a believer. Yet I find as time goes on, it is getting more difficult to recall. I'm glad for that.
The thing is, when you are a believer, you cannot conceive of anything more empty than losing faith. But when I let my faith go, I felt amazing. It was such a weight lifted. My brain worked better and without the constant struggle of cognitive dissonance. They don't understand that. It leads to posts similar to what is on this thread--pity. And it's kind of funny, because they have no clue to how liberating walking away really is.