Belief in the Trinity is a necessary condition for salvation? That's so absolutely unbiblical it scares me. Scripture is at least a little vague on the nature of God or there would be no discussion whatsoever. You had better read Jesus again and find out what it really takes for someone to be saved. *Hint* It isn't "belief".
I think that you misworded this. Belief or faith involves trusting something. If you truly belief that one need not trust God for their salvation, then you are far away from scripture.
I know plenty of "believers" (Trinitarians all) who will be consumed by the fires of hell because they think, just like Israel often did in the OT, that "belief" in God and identification with His people (for Christians, going to church) puts one in a right relationship with God.
In this you reveal your Shibbolath. Apparently not one of the Oneness believers are living a lie.
We both know how that worked out for ancient Israel. Exile? Diaspora? Captivity? Yes, Yes, Yes. How many Christians today think that they are forgiven for everything and that they have perfect standing before God? Practically all of them. And yet..."if anyone says that he is without sin he decieves himself and the truth is not in him. But if we confess our sins, He is faithful and just, forgiving our sins and cleansing us from all unrighteousness." The modern evangelical church makes me so angry for exactly this reason, teaching that a confession of belief in Jesus, if sincere, magically makes one right with God and, for the Calvinists out there, ensures forever that one is "safe". Mind you, I'm not talking about Christians who think they can go on blatantly sinning. I'm talking about "good people", average Christians who "clean up their act" but never clean up their hearts.
The problem with this is that we cannot see into their hearts. Only God can make that judgement. Yet you are making it, and broadly so. Can we turn the same spotlight on you. Can we assume that in spite of you "cleaning up your act", that you have not cleaned up your heart? Only God can judge the heart.
Point is, you can believe in the Trinity and confess Jesus and still go to hell. You can also believe that God is numerically one (or three), and Jesus is Lord, and be saved if you are obedient to Christ's FULL teaching. Understanding the NATURE of God is not a requirement for salvation; rather loving God, repenting your sin, and obeying Christ as Lord.