Is it or not an established fact about the Bible?
It is not an established fact that the First Council of Nicea did anything about the Bible, It was concerned mostly with the Creeds. And JW’s don’t like what was decided! The declaration that Christianity was the established religion in the Roman Empire gave a great boost to it and led to much activity in copying the bible and our earlies complete manuscripts of the New Testament come from that time. After allowing for a bit for difficulty with original text and some bigger issues about how to translate certain words, what you see is what you get. To most, not all, Christians, Jesus is the Word of God and even when that is accepted there is still room to debate the actual meaning of passages. That is why I find it fascinating.
