How do we know the Bible is really God's words?
2 Timothy 3:16-17 says: "All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work." At the time it was written, the word for Scripture is the same word used to describe the OT Scriptures. Therefore, the early apostles recognized the divine authorship of the OT. Jesus also recognized the OT as Scripture having divine authorship in several places in the NT: "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished." (Matthew 5:17-18) "Scripture cannot be broken." (John 10:35) “And beginning with Moses and all the Prophets, he interpreted to them in all the Scriptures the things concerning himself.” (Luke 24:27) "Have you not read that he who created them... said.." (Matthew 19:4-5). Therefore, both the apostles and Jesus Himself recognized, quoted and taught from the OT as divine authored Scripture. What about the New Testament? "Now we have received not the spirit of the world, but the Spirit who is from God, that we might understand the things freely given us by God. And we impart this in words not taught by human wisdom but taught by the Spirit, interpreting spiritual truths to those who are spiritual." (1 Corinthians 2:12-13) “And we also thank God constantly for this, that when you received the word of God, which you heard from us, you accepted it not as the word of men but as what it really is, the word of God, which is at work in you believers.” (1 Thessalonians 2:13) “And count the patience of our Lord as salvation, just as our beloved brother Paul also wrote to you according to the wisdom given him, as he does in all his letters when he speaks in them of these matters. There are some things in them that are hard to understand, which the ignorant and unstable twist to their own destruction, as they do the other Scriptures.” (2 Peter 3:15-16)