Are you saying that man cannot exercise faith unless he is a Christian?
Nope. I am saying that unless a Man is Regenerated, he has no Faith within himself to exercise unto Repentance and Adoption into the Family of God. Regeneration creates Faith in those who were formerly Spiritually-Dead.
Once a Man is Regenerated, he then does Repent and is Adopted (pretty much all in the same instantaneous progression of mental events).