Actually my response really was a reaction to the implying that we are not Christian because we do not sing Christmas carols. There are enough differences in doctrine that we do not have to stoop to inaccurate implication to prove Mormons teach some things differently.
So my statement that we do TOO sing Christmas carols (I think I called them hymns) was really just pointing out the lie. I would think that is enough, and that a more vigorous defense was not needed.
Maybe I mis-estimated the logic facilities of the audience.
T.P. the reason Mormonism is not Christian has nothing to do with whether Mormons sing Christmas carols. It has to do with the fact that Christianity is a monotheistic religion and Mormonism teaches that there are many gods. There are many other differences, but the monotheism/polytheism thing is a deal-breaker.
But just because Mormonism is not a Christian religion doesn't mean we can't be friends.