I really don’t care in the end whether someone says they are Christian or not. I care only if they try to live in accordance with what Jesus taught and how he lived - living to the best of their own understanding and ability. I prefer the Buddhist or Muslim who is living a “Christian life” to the Christian who is not striving to do so - even if that Christian is Mormon.
Arguments over being called Christian are too much like, “We have Abraham for our father,” for me. Nearly always it carries a “therefore I am saved while you are damned” implication that is the real un-Christian statement. That goes beyond just giving offense. In other words, if “Mormon” functions as a curse from someone's lips, in the true scriptural sense of the word, it’s wrong and un-Christian; if “Christian” functions as a curse from our lips, it is just as wrong and un-Christian.