1) What really grinds my gears is when people accept only half of their religion.
"Yes i know the world isn't 6000 years old, and that it's unlikely that man could separate a sea of water, but Jesus was real!"
Commit to the belief or accept the falseness of your God/Faith.
2) But possibly what grinds my gears greater, people who believe everything they are told.
3) One more, "n00b athiests" -Sure they annoy me a bit, but people with a high knowledge should stop trying to act superior towards them, they're a hell of a lot smarter simply by not believing instead of believing, so instead of hatin' lets embrace them and teach them :) just don't preach them!