Does it really matter? I have a hard time believing that telling Mormons that they aren't Christian will convince them to give up their faith.
Gabu, people that say Mormons aren't Christians are using an age old tactic of anti-Mormons. They say the Church doesn't worship Christ and that they're the only ones who do. This sort of attack on the Church is as old as the Church itself.
I know that. And what I'm saying is that the reason people say that is either for one of two reasons:
1. To make themselves feel better, or
2. To attempt to convert Mormons to another branch of Christianity.
Those who are doing it for reason #1 are just pathetic and ought to be ignored, and those doing it for reason #2 are actively hurting their cause by immediately putting Mormons on the defensive the moment they open their mouth. That's what I'm saying.