Well, Kevin, I will give you a straight answer to your question.

...But after this: I think you need to take into account the fact that most theists don't actually think that everyone is going to hell but their fellow theists. From my experience, most sensible theists say "It is between you and God".

As far as why one chooses one religion or another, it is as simple as reading the doctrine of a religion.
You read and agree, or you disagree and move on.

If you are determined to adapt the scientific method into a belief system, there is really no point in discussing religion at all.

Why open your mouth if you already know that you are not going to be satisfied?

The way I see it is thusly:
People are irrational by nature, but have the ability to recognize their nature for what it is.
The best you can hope to do is come to terms with what it means to be human, and try to improve yourself.