…we know that God does not lie. I and my neighbor and, in short, all people, may err and deceive. But God’s Word cannot err. (Large Catechism – Part 4, par. 57).
We receive and embrace with our whole heart the prophetic and apostolic Scriptures of the Old and New Testaments as the pure, clear fountain of Israel. They are the only true standard or norm by which all teachers and doctrines are to be judged. (Formula of Concord: Solid Declaration, par. 3)
God’s Word alone should be and remain the only standard and rule of doctrine, to which the writings of no man should be regarded as equal. Everything should be subjected to God’s Word. (Formula of Concord: Solid Declaration, par. 9)