Look it up.
"Jesus and Satan are spirit brothers and we were all born as siblings in Heaven to them both." (Mormon Doctrine. p. 163.)
"God used to be a man on another planet..." (Joseph Smith, "Mormon Doctrine." Orson Pratt, "Journal of Discourses," vol 2, p. 345.)
Now, get this: "One of the most fallacious doctrines originated by satan and propounded by man is that man is saved alone by the grace of God; that belief in Jesus Christ alone is all that is needed for salvation." ("Miracle of Forgiveness," Spencer W. Kimball, p. 206.)
Calling yourself Christian and tossing in little out of context "proof texts" from the Bible is exactly what heretics and non-bel;ievers have done for centuries. Whatever Mormonism is, it is not remotely Christian in its doctrines. It is misleading and dishonest for Mormons to pretend they are Christian. Now, their salvation or not is God's business. We cannot speak to that. But, we can name heresy and false doctrine and call it what it is...nonsense.