So faith comes from hearing, that is, hearing the Good News about Christ.
Romans 10:17 (NLT)

For by the grace given to me I say to every one of you not to think more highly of yourself than you ought to think, but to think with sober discernment, as God has distributed to each of you a measure of faith.
Romans 12:3 (NET)

The apostles came up and said to The Master, “Give us more faith.” But The Master said, “You don’t need more faith. There is no ‘more’ or ‘less’ faith. If you have a bare kernel of faith, say the size of a poppy seed, you could say to this sycamore tree, ‘Go jump in the lake,’ and it would do it.”
Luke 17:5-6 (MSG)

In reply Jesus said to the disciples, “If you only have faith in God, this is the absolute truth, you can say to the Mount of Olives, ‘Rise up and fall into the mediterranean,’ and your command will be obeyed. All that’s required is that you really believe and have no doubt!
Mark 11:23 (TLB)

Listen to Me! You can pray for anything, and if you believe, you have it; it’s yours!”
Mark 11:24 (TLB)