MS Lutherans, sounds like a program from Microsoft I don't want.
That verse is meant more like what Raphael said so nicely.
You have a different problem, its with other believers. What doctrines do they not agree with you about?
In cases like this, maybe you need more armor than defense, if they truly think you are not "going to heaven." I've had that same experience before, its not pleasent. Anyone who trusts in the Lord Jesus alone is the one who is saved. Maybe they ought to examine themselves, see if they be in the faith. Lutherans claim the name of a man, Luther. I find that strange right away.