On the backfire effect

In my experience, this is very, very true.  It's the reason why I have very few honest-to-god core beliefs, and mostly I try to operate from a very small set of concise beliefs and extrapolate from them.
If someone says something that hits you really hard and you feel a visceral need to argue against, I recommend treating it like a (good) therapist would.  Try to figure out why the other person holds that belief.  Step into their shoes...does the belief help them in their life in some way?  Signify belonging to some group?  Keep them from having to wrestle with something?

And look at your own questionable beliefs with the same inquisitive eye.  Arguments are good for you, especially if both you and the person you're arguing against come away having learned something about yourselves and the world.