Theists: How can predetermined fate and free will coexist?

[RoadRunner79]

To the envelope question.... I don't see how an unknown envelope (no matter what it contains) can effect your choice or free will.

Then you're either not very intelligent or willfully ignorant. If the envelope says you're going to walk through door A, then your will is already determined to walk through door A, you can't walk through any other door but A, in that case it is isn't free. It is your will, but it isn't a free will because it's determined. It seriously doesn't get easier than that, if you don't understand that, there's no hope.

So; what is the difference if you go through door A and there is no envelope with the prediction? What does it mean that you do not have freedom in this sense?
I could will to fly like a bird, but I'm not free to do so.