You talk about teaching false doctrine and being damned. Here is a list of false doctrines that if someone teaches he will be damned. And there is not one of these that I have ever known to be taught in the Church, but I am giving you the list for a perspective because of what will follow. Teach that God is a spirit, the sectarian trinity. Teach that salvation comes by grace alone, without works. Teach original guilt, or birth sin, as they express it. Teach infant baptism. Teach predestination. Teach that revelation and gifts and miracles have ceased. Teach the Adam-God theory. (That does apply in the Church.) Teach that we should practice plural marriage today. Now any of those are doctrines that damn. They are what I just read about from 2 Nephi 28.