Most protestants adhere to sola scriptura. I guess you're an exception.<quoted text>
I never said I can prove from scripture it was the sole authority. I said if God's Word it good for training in righteousness, why use anything else?
I guess you would if you were catholic.
Why 'use' anything else? Because the gospel was preached orally for a decade or more before a single passage of the NT was written. The oral preaching of the Word of God by the same men who wrote the NT is no less valuable than the written Word of God. That's why.