Very few people care about defending the doctrine of God against those who teach heresy. Adn those that point out the heresy are not welcome.
I've never believed that a person can lose his or her salvation - there are too many passages that indicate that Christ cannot lose one of His own. So the last straw in leaving my Arminian church was when my kids and I were talking about their childhood and I asked if they remembered the moment that they "got saved". My son could tell me where he was, what he had been doing, who was there.
My daughter said, "What do you mean? Do you mean the first time, or all the other times?" The surety of her salvation (to her mind) depended on how many times she had "gone to the alter" - this was the consequence of this bad doctrine.
What are the consequence of having "relationships" with those who deny the Trinity?
James White says (In "The Forgotten Trinity):
True worship must worship God as he exists, not as we wish Him to be. The essence of idoloatry is the making of images of God. An image is a shadow, a false representation. We may not bow beforea statue or figure, but if we make an image of God in our mind that is not in accord with God's revelation of Himself, then we are not worshiping in truth. Since sin and rebellion are always pushing us toward false gods and away from the true God, we must seek every day to conform our thinking and our worship to God's straight-edge standard of truth, revealed so wonderfully in Scripture.
(page 195) Look at the "gospel" message of every single group that denies the doctrine of the Trinity. You will find error and perversion in every group. Why? Because the true Gospel must be based upon the work of the one true and triune God. Without that basis, the Gospel cannot stand. Look at Mormonism, which denies the pillar of monotheism: the Gospel becomes the means of becoming a god. Look at the Witnesses: the Gospel is a mere appendage, a message of how we can live forever in a paradise earth. Such is what happens when the Redeemer becomes Michael the Archangel, and the Spirit becomes an impersonal active force. And in the Oneness groups the Gospel becomes legalism, replete with "necessary" things one must "experience" to be truly saved.
Bad doctrine has consequences - twisting the Gospel to fit our own desire about how it should look - has consequences.