No, it's not WHAT it's WHO is that authority. Simple answer...GOD. Do you seriously think that He went to all the trouble to verbally inspired the writers of Scripture over thousands of years, ensuring that His word was established forever, and then leave it up to fallible, sinful men to decide what was and wasn't God's word? Here's what we are to consider about the sacred Scriptures:
The secret things belong to the LORD our God: but those things which are revealed belong to us and to our children for ever, that we may do all the words of this law. (Deuteronomy 29:29)
People of God received the word of God because it WAS the word of God. He didn't need our permission to preserve and protect it. Almighty God through Paul told the Corinthians:
Now some are puffed up, as though I would not come to you. But I will come to you shortly, if the Lord will, and will know, not the speech of them which are puffed up, but the power. For the kingdom of God is not in word, but in power.(I Cor. 4:18-20)
Those who speak the words of God have the power of God behind them. The gospel is the power of God unto salvation to all who believe.
So which canon of Scripture did God give us?
I contend that the canon of Scripture that God gave us is the Catholic Bible. God's infallible Church ("the pillar and foundation of truth") tells us so.
You contend that the abridged, Protestant canon of Scripture, is the Bible that God gave us. Your infallible authority for canonicity is... what?