Why is it so easy to trigger a religious person?

So much anger, judgment, finger-pointing and self-righteousness. I wonder how many responders to this even cohabitate with people whose opinions differ from theirs on the daily. It shouldn't shock me, but really, I wonder if some of the responders to this can function in this world of differences in a healthy way. Anyone of any faith, anyone who reject faith, can be equally certain of themselves. We have to leave room for personal choice, or it all falls apart. Eek.