Why then, is it so wrong for someone to be of a different faith? If true is true, and no one can be, or need be, certain enough of it to be able to prove it, what is the big deal about different religions, or just believing in God?
stuartcr, I just look at it this way: The Spiritual knowledge that we humans need is contained in the Holy Scriptures, in which God tells us of Himself, of his creation, and of man "truly, but not exhaustively." This is God's Holy Word to us, spoken to us through the prophets, patriarchs, and the Apostles. God is the Author of all that there is, in heaven and on earth: He is Truth. To me, the really important thing is not to which religion or confession one belongs. What is important is to adhere to the spiritual wisdom of God's truth as given to us in the Holy Scriptures. Indeed, they give us everything that is needful for man to be fully human. Man is made in the image of God, and so just naturally made to resonate to God's Truth. We find that Truth in the Holy Scriptures.
The faithful lovers of this Truth are all united in the One Body of Christ, regardless of which confession each of us professes.
Anyhoot, that's how I look at it, FWIW.