All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the man of God may be thoroughly equipped for every good work.

How do you come to know this? The holy Gospel tells me. God Himself began to reveal the gospel already in Paradise; later, He proclaimed it by the holy patriarchs and prophets, and portrayed it by the sacrifices and other ceremonies of the law; finally, He for filled it through His own dear Son.