There is a point where some individuals have direct witness of God. For those people, their knowledge obviates faith. For anyone who has not had direct experience, I agree that their faith can simply be the product of intellect or belief. I was agnostic for many years, later acquired intellectual belief, grew in faith even as a doubting Thomas, but was blessed by direct contact that was truly unmistakable. I don't have any material evidence to share, but offer my testimony for what it's worth. It is possible that you may receive the proof you seek. If you are like me, the form will surprise you.