Answer by Jim Ashby:
Thanks for the A2A, Rajesh P Mukkath and Farhan Arshad. I appreciate it!
Because they don't understand what it means to be open-minded. They're indoctrinated into a religion and commiserate with others who are similarly indoctrinated. On top of that, in social situations, people who don't share their beliefs normally avoid discussing them for the sake of peace and harmony.
They live in a bubble in which they're so unaccustomed to criticism of their beliefs that they actually believe their beliefs are sacrosanct: above criticism.
To make matters worse, they don't understand that faith is belief without objective reason: evidence or rational explanation. If you have faith, why the heck put yourself in a position where you need to provide what you don't have? Cognitive dissonance much?
Between themselves, they engage in Godspeak so much that they actually believe they know God. They think prayer is efficacious; that they're going to heaven; that the creator cares about them; and that Jesus forgives their sins.
But when faced with atheists — most of whom were deconverted from one religion or another — they're out of their element. Instead of their mutual admiration society, they're faced with freethinkers and actually need to rationally justify their claims.
And they can't. How can they? We're talking about supernatural deities for Christ's sake. No evidence. Hello? Anybody home? Nobody can substantiate anything supernatural. THAT'S WHY THEY NEED FAITH! They hate that faith has no objective support. But what can they do about it? Well, if you can't rationally defend your position . . . what do you do? Blame the freethinkers. Cast aspersions upon them. Anything but engage in rational debate. We all know how that's going to end up.
If you had no evidence for what you believe, you'd be thin-skinned too.