What does the Bible say about Itself?
Old Testament
A large part of the Bible contains prophecy. And 2 Peter 1:20 says that ‘no prophecy of scripture came about by the will of man, but men spoke from God as they were moved by the Holy Spirit.’ All prophecies made by scripture are therefore the words of God, not men.
In keeping with this, Old Testament prophets are consistently portrayed as being the mouthpieces of God, proclaiming His very words (Exodus 4:10-17; 1 Kings 22:8-16; 2 Samuel 23:2; Isaiah 59:21; Jeremiah 1:9; 25:1-13; 31; Ezekiel 23:26,27). And looking back over Israel’s history, Zechariah blames the nation for ‘refusing to hear the words which the Lord had cried by the former prophets’ (Zechariah 7:7,12). Given this, it is perhaps not surprising that the phrase, ‘thus saith the Lord’ appears more than 2,600 times in the Old Testament!
Elsewhere in the Old Testament, we are also told that God does absolutely nothing without firstly revealing his plan to His servants the prophets (Amos 3:7). We are also told that these revealed things belong to believers in all ages (Deuteronomy 29:29), having been passed down to us in the scriptures. These scriptures, Paul tells us, ‘are the very words of God’ (Romans 3:2).
This makes it clear that God’s written words are not limited to biblical prophecy. The Bible also tells us that the Mosaic Law (Psalm 119:13 etc.) and other books, such as the Psalms (Act 4:25; Hebrews 3:7) are God’s own words. This is further evidenced by the fact that even where words are attributed to others in their original contexts, those scriptures are still referred to as the words of God (Matthew 19:4f and Genesis 2:24; Hebrew 3:7 and Psalm 95:7). This inseparable connection between the scriptures and the word of God is reinforced by verses that personify the ‘the scripture’ and directly equate it with God (Romans 9:1; Galatians 3:8).
The New Testament
As with the Old Testament prophets before them, Jesus’s disciples also became God’s mouthpieces on occasion, when Jesus told them that it would not be them speaking, but ‘the spirit of your Father speaking through you’ (Matthew 10:20).
As regards the books of the New Testament, the gospels are referred to as 'scripture' (Luke 10:7 and 1 Timothy 5:18), as are Paul’s letters (2 Peter 3:16). And 2 Timothy 3:16 says that all scripture, Old and New, is ‘God breathed’ and therefore ‘useful for teaching, rebuking, correcting and training in righteousness’.
It is important to note that Paul does not say here that the men who wrote the scriptures were inspired, although undoubtedly they were. What he is telling us is that the words of the Bible are God’s words; He breathed them.
The 'filtered through human beings' raises some interesting questions. Man is sinful, changeable and error prone. So is it inevitable that the pure water of God's word would be contaminated beyond recognition if it were filtered through human beings? And if that is the case, why would God choose to do this?
Jesus said that heaven and earth would pass away, but His words never would. If filtering these words through sinful human beings always distorts God's words, then Jesus's words would never have left the 1st century AD.