It is natural. Doubt is peculiar - irrational in fact. It is the only thing that ever surprised Jesus. Can Believe Talking of saints is the next thing. People confuse faith and virtue.
Faith is there.
Faith is just faith. Virtue is developed. Faith doesn't come as does learning the piano grade by grade. We can have faith even when we know we are not very good. Nobody is good, but Christ taught us that all can believe.