Let us beware of attempting to add anything to the word of God, as necessary to salvation. It provokes God to give us over to judicial blindness. It is as good as saying that His Bible is not perfect, and that we know better than He does what is necessary for man’s salvation. It is just as easy to destroy the authority of God’s word by addition as by subtraction, by burying it under man’s inventions as by denying its truth. The whole Bible, and nothing but the Bible, must be our rule of faith nothing added and nothing taken away.

~ J.C. Ryle

Expository Thoughts on the Gospels: Mark, [Carlisle, PA: Banner of Truth, 1985], 138, 139.