What is written directly to the Jews, belongs to and is for the Jews. What is written directly to the Gentiles, belongs to and is for the Gentiles. What is written directly to the Church of God, belongs to and is for the Church of God. What does God mean when He tells us that the visions shown to Isaiah was concerning Judah and Jerusalem? It was not addressed to us or written concerning us, but it was addressed to and concerning Judah and Jerusalem. It would be dishonest for the Church of God to interpret to the Church of God what God said concerns Israel.
However, the whole Bible is God-inspired, as both Paul (2 Timothy 3:16-17) and Peter (2 Peter 1:16-18) say. Every passage has God's truths embedded in it. That's one of the criteria that the early church used to determine which books to include. Where did you get these ideas about the Scriptures?
2Pe 1:19 And we have the prophetic word more fully confirmed, to which you will do well to pay attention as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts,
2Pe 1:20 knowing this first of all, that no prophecy of Scripture comes from someone's own interpretation.
2Pe 1:21 For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit.
2Ti 3:16 All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness,
2Ti 3:17 that the man of God may be complete, equipped for every good work.
Note that Paul says that we must become "complete" and "equipped" by God's Word "for every good work." That means we need spiritual progress in practice. I still need it at 82 after 66 years of being a Christian. If Paul says that he was still imperfect in Philippians 3:12-14, I'm not going to claim that I am, because I know my sins. Paul describes his and our "not-yet-perfect" situation in that passage:
Php 3:12 Not that I have already obtained this or am already perfect, but I press on to make it my own, because Christ Jesus has made me his own.
Php 3:13 Brothers, I do not consider that I have made it my own. But one thing I do: forgetting what lies behind and straining forward to what lies ahead,
Php 3:14 I press on toward the goal for the prize of the upward call of God in Christ Jesus.