A8: First, that claim itself is not in Scripture.
HD: Not only is the perfection of the word talked about in scripture, the Church fathers endorsed that view. If you think man's wisdom is perfect, I would read 1 Cor.
The claim that is not in Scripture is not that the Scripture is perfect, but that "All others can be subject to error and should be questioned against the scripture". The Bible never says that the Sacred Magisterium is subject to error, or that the Sacred Tradition is subject to error, or that laymen should use their own interpretations of Scripture to question or critically evaluate the Sacred Tradition or the determinations of the Sacred Magisterium.
-A8
You won't find the Sacred Magisterium in the scripture either. I did a word search. The Church told you it.
We can argue for the next six months and 3,000 posts about the authority of the scriptures and never get anywhere. The fact is that the Catholic Church claims that every decision they make is based upon the scripture as has been interpreted through the lens of time by their learned scholars who know better then everyone else and were led by the Holy Spirit in creating the right doctrine. Well, I happen to believe that God will lead me to all truth necessary for my walk with Him if I dillegently study His word. You trust the Church to tell you what is right. I trust God to tell me what is right.