Why would you think that Mormons are not Christians? They believe in Jesus Christ just like you and I do. They believe that Mormon men can become another Jesus Christ of their own planet and that they can take their wives with them and be lord of that planet.
If this is contrary to Mormon teaching, please, a knowledgeable Mormon, explain my misunderstanding!
Two Mormon missionaries visited us when we were newly married and were explaining their beliefs to us. They proceeded to tell us that there were three distinct gods, as God the Father appeared biblically to man as an older man. God the Son appeared as a young man, Jesus. At that point, I asked if the Holy Spirit was a bird, as he appeared as a dove. With that, my husband and I couldn't stop laughing. Two very frustrated young men packed up their charts and books and did as Jesus commanded and shook the dust from their feet and took a speedy exit!
We weren't laughing at them, it is just that their explanation struck us as very funny.