It's a tough situation. Defending belief is an unenviable position. Human progress is due to gaining understanding through testing and experience. Belief is on the losing end of this process.
I gave up trying to convince people a long, long time ago.
Belief can only be undone by an internal process of self-realisation.
Why is the Bible correct? -> Because it is the Word of God -> How do you know God made it -> Because...
1) The Old Testament predicts events that come true in the New Testament
2) How could a bunch of random people create such a perfect book unless it's divinely inspired
3) Historical facts / evidence point to its truth
4) It's just my faith, and there's no harm having something to believe in
5) Because it says in the Bible it's true
6) Why not believe in it? If it's right then I'll go to heaven. That's better than not believing at all
7) It wouldn't have become so popular / so well-preserved if it isn't true
8) Because it's full of wisdom
9) Because it makes my life better to believe in it
10) There's no evidence it's not true
This chain of circular logic has to be undone through self-initiative.
No matter how many facts or how much logic you throw at someone, there are always methods to rebut it that are consistent with their faith. You could do the same process for the Qur'an and other holy books.