Oneness

Something I’m grappling with today: Oneness.
Oneness is the belief that God is not coequally and eternally existant as three persons (Father, Son, Spirit), but that He is instead ‘One God’ who simply manifests Himself as three persons (Father, Son, Spirit).
It implies that God simply wears different hats to potray His different ‘characters’ whenever He feels like it.
While the Bible is very clear that God is One; and is coexistant as three unique persons: See my Statement of Faith to the left to fully explore this idea.
Now I understand that the doctorine of the Trinity is VERY confusing, and that new-uninformed Christians may have Oneness type beliefs. But when confronted with the truth, upon studying Scripture and being discipled under Godly leaders, a new Believer must submit to the teachings of Scripture- ones which have been held reverantly for nearly two thousand years of Church history.
So the issue I’m grappling with is,” are Oneness believing ‘Christians’—Christians? Is this a closed-fisted issue of the Christian faith? I believe it is. Those who teach such things are clearly heretics.
There are many more points I could make regarding Oneness Christians, but this is simply an overview of the issue and the things I am trying to bring into the light.
So while it is clearly heresy and should not be promelgated, the issue of whether these people are saved are not thankfully lies in the hands of God and not mine.