I am going to go and buy this bible with my tickets!
I wouldn't do that, you might be buying your life away
If you dedicate your time to religion it might also waste your time doing something else
In this sense tom is going to go any buy a bible with his tickets that he got from "whitewashing" the fence.
When he is saying that he would buy is life away that is referring to that when you start religion you are putting a lot of time and effort into what you are doing. This mocks society because a lot of people think religion is useless and a waist of time.
twain I think is trying to say that religion is a waste of time and that it will take a lot of effort. you could be doing something else that is more efficient