I fear it's because religion is man's attempt to reach God, and when he feels he has succeeded, he cannot abide anyone else's claim to have done the same.
I would fix other people's lines if they asked me on occasion. The hard part of writing is the architecture of it, getting the story and structuring it. Not the tweaking of lines.
We were all thrown together on this show very rapidly, there was casting then a few days later a meeting where we all got to read the scripts and meet each other. Literally days after that we were on our way to Dallas.