No, it is not necessary for salvation and I am going to make it clear why.
One thing to notice is that nobody can really show any real justification why it should be a salvation issue.
Time and time again, in fact, I have not only provided Scripture, metaphysics, and connections throughout the Bible which outline explicitly that Jesus is NOT God, and the only thing I have ever gotten in return from trinitarians is utter denial and bigotry.
The trinity concept is fruitless. It does enlighten one on anything and only causes confusion. Nothing good has ever come out of that cursed theology. It is quite vain, and it's ONLY usage in it's entire history has simply to been as a blunt object to bash others with.
It was founded on highly questionable grounds, and is simply absurd that it would be a salvation issue by any means. In fact, the one's who go on to bash others with it are the one's who should be questioning their salvation because it is obvious that such people are full of dead bones.
The truth is that the Bible does not 'clearly' lay out a trinity concept. A lot of Jews were worshiping angels, or more specifically, a Sephiroth Trinity after the events of Jesus. A lot of Jews connected that concept to Jesus. John and Paul both in their lifetimes opposed this greatly, and yet because people had an obsession with trinities and inter-changeable beings in every major culture it was no surprise that the Greeks would want to make an idol that many people would marvel at. They even tampered with Scripture to relay this image. And that is a mighty, mighty sin.
I did not reject the trinity initially, and when I did, it wasn't out of simply wanting to be on the contrary. My reason for putting away that triangle is because I snapped out of that daze upon realizing it's origin.
When one comes to terms with the fact that the Church was cursed from the start, one will see that it's central doctrines are as well. No sooner were the Church and it's doctrines established did the world fall into the Dark Ages and people were being persecuted over these doctrines.
It cannot be any clearer that it is not a holy concept, and I am appalled by the amount of people who have the audacity to continue some idea that it is a requirement for salvation. It is man-made, was obviously not spiritually given by the Church, and as I said, is fruitless.
If one still chooses to believe in the trinity, I see no real reason why that would be a salvation issue, but if one has any fear of God whatsoever, they will sow their mouths shut when someone says they do not believe it because you would be doing nothing then making a dividing line over virtually nothing.
