One of the first things I did when I was trying to face my doubts about the bibles inspiration was to read it. As JWs we are always told to read daily, but you can't get much sense of context or continuity when you read a chapter or two a day. So, I knew if I was going to give up on the religion and/or the bible it would only be after I had actually read and researched. The NT was read by me in just a couple weeks. I really poured myself into doing it. There are many inconsistencies in it, but for me the proof that it was not inspired came in what would be the most important verses in the entire bible.
God literally speaking has to be the most important verses in the bible. God speaking about his son's baptism and heard by others? Again, even more important!
So, were the bible writers present at Jesus baptism? It does not appear to me they were. (But, it doesn't impact this point either way.) With the writers of the book not being there, then Holy Spirit would have to inspire them to record what god said at that most special baptism.
Each bible account is different...
God if he were literally guiding what was being written would have ensured something as monumental as him speaking at his sons baptism was correct. But, he didn't. It's recorded completely different. In one account he speaks personally to his son. He commends and praises him in an endearing way. In another he speaks to the crowds as if to tell them the truth, or convince them. When you consider the fact that the single most important verses in the bible are different, then how could the hand of god have been guiding and inspiring the bible?
Then I read the accounts of Jesus death. Jesus the ransom sacrifice's last words! Completely different. Different words, different emotions, different in every way.
I'll never forget how I felt when I realized this.