Galatians 1:9 As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let them be under God's curse!
"It should be noted that though many might write concerning Catholic truth, there is this difference that those who wrote the canonical Scripture, the Evangelists and Apostles, and the like, so constantly assert it that they leave no room for doubt. That is what he means when he says 'we know his witness is true.' Galatians 1:9, "If anyone preach a gospel to you other than that which you have received, let him be anathema!" The reason is that only canonical Scripture is a measure of faith. Others however so wrote of the truth that they should not be believed save insofar as they say true things." (St. Thomas Aquinas, Commentary on the Gospel of John 21) [(Romae: Marietti E ditori Ltd., 1952) n. 2656, p. 488.]
In Latin: "Cuius ratio est, quia sola canonica scriptura est regula fidei."
Go figure! Sola Scriptura way before Luther! And in comments made on Galatians 1:9 no less!
Galatians 1:9 As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let them be under God's curse!
How does this prove Luther's tradition of the Bible alone as the sole or ultimate rule of faith?
The quote you provided from St. Thomas, below, seems to be popular on Protestant apologetics boards, but wildly misinterpreted, misunderstood, or simply cut and pasted without understanding.
"It should be noted that though many might write concerning Catholic truth, there is this difference that those who wrote the canonical Scripture, the Evangelists and Apostles, and the like, so constantly assert it that they leave no room for doubt. That is what he means when he says 'we know his witness is true.' Galatians 1:9, "If anyone preach a gospel to you other than that which you have received, let him be anathema!" The reason is that only canonical Scripture is a measure of faith. Others however so wrote of the truth that they should not be believed save insofar as they say true things." (St. Thomas Aquinas)St. Thomas is comparing apocryphal writings to canonical writings (Sacred Scripture). Obviously, they're categorically different. He certainly isn't saying that the Bible is the sole or ultimate rule of faith.
I don't see how Gal 1:9 or the quote from St. Thomas even hint at Luther's tradition.
And there is simply no evidence of Luther's tradition prior to Luther.
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Here are more quotes from St. Thomas that prove that he did not subscribe to Luther's tradition:
ST Third Part, Question 25, Article 3The Apostles, led by the inward stirring of the Holy Ghost, handed down to the churches certain instructions which they did not leave in writing, but which have been ordained in accordance with the observance of the Church as practiced by the faithful as time went on. Therefore the Apostle says: 'STAND FAST, AND HOLD THE TRADITIONS WHICH YOU HAVE LEARNED, WHETHER BY WORD' -- that is by word of mouth -- 'OR BY OUR EPISTLE' -- that is by word put into writing (2 Thess 2:15)....
ST II-II, Question 5, Article 3
The formal object of faith is Primary Truth as manifested in Holy Scripture and in the teaching of the Church which proceeds from the Primary Truth. Hence, he who does not embrace the teaching of the Church as a divine and infallible law does not possess the habit of faith.