It must be noted that the trinity doctrine was introduced after the death of the apostles and early Christians. Even then, it took centuries to define and to refine this teaching. It caused not only the rift between the trinitarians and arians in the 4th century, but the specifics of it became a controversy between the Catholic and Orthodox branches of Christendom. And all through this historical period it was rejected by various religious groups.
What bothers me most is that some Christians insist that it is the "central doctrine of Christianity." They believe without this teaching one can not be a Christian. To me this seems to be the same mentality of the Watchtower Society who insists that only its way is "the truth."
Trinitarians are not beyond deception either. One only has to consider the insertion of l John 5:7 in the older versions of the Bible or the treatment of John 1:18 in the newer ones. I certainly don't defend the Watchtower's notorious mishandling of quotes in its publications. But there is enough blame to spread around to include others.