Why do you need to pay for enlightenment?

You don't. Tithing was meant as a way to support the church. The church, as I understand it, is not contained in a building, but in the body of a believer. We are the church. So my tithe goes where it's needed. If I know of someone who can't pay their electric bill, my tithe helps them. If someone needs groceries, or a place to live, I put my tithe towards that. Hope this answers what you were asking.