There are a combination of factors involved in determining whether the whole of The Bible (the Hebrew scriptures plus the Christian Greek scriptures) can be believed as inspired of God. If God has inspired all of the various writings that make up what later came to be called The Bible, then we can confidently quote it as the word of God, and not just the word of men.
This means that if we just quote bits from the Bible that claim those words are inspired of God, that - in itself - will not constitute sufficient evidence. Ideally, we should find so much evidence of the authenticity of what the Bible says (internally and externally), we could point to that as proof sufficient. Then we would not be relying on what this man, or that man, or another woman says.
This is a problem with various writings. There are other scriptures apart from The Bible, whose proponents say things such as, The Book of Mormon says in its last book called Moroni, ch.10 vss.3-5, that God bears witness of the truthfulness of the Book of Mormon to all who ask Him in faith. I've got a copy of the Book of Moron here, and the charge is made that if you are sincere in asking, with faith in Christ, then the Holy Spirit will let you know the truth of all things contained in the Book of Mormon.
Now, being a Christian for over five decades, and having been brought up on the Bible for nearly two decades prior to then, I immediately recognized those verses as being 'lifted' in large part from the far more ancient Bible, and I found very many other similar examples, all written in the King James style of writing. But here's the rub: those who uphold the Book of Mormon as fitting the bill as inspired of God because it says so, deny the same truth applies equally to the far older Bible that originally made such claims. They say the Bible is only accurate and inspired of God in so far as it has not been corrupted, Joseph Smith's annotated version of The Bible being what they go by. I mention this because wherever people disagree with bits in the Bible, they try to direct one to their own leaders' writings, saying these 'explain' the Bible properly. The question here is that who tells us something is inspired of God - or not - need not prove anything. We may be no further forward if we go by what other people say.
Anyone wanting to know if the whole Bible is inspired needs to start reading it prayerfully for themselves. And, given that Jesus Christ said no-one can come to God the Father except through him (John 14:6), and that only God the Father draws people to Christ (John 6:44 & 65), what the Bible says about the Father and the Son is the only authoritative source. Going anywhere else for information (either other literature, or to other people) could lead one astray. If the whole Bible is the inspired word of God, and God cannot lie (Romans 3:4), then it will lead us to the Christ of the Bible, and God the Father. There's no short-cut. Start reading in order to discover the Father and the Son (the gospel accounts are ideal for that) and then you can make your own mind up once the Holy Spirit who inspired it brings you to spiritual life.