This is a somewhat difficult question to answer given the syncretistic nature of our society. Although Mormons acknowledge Jesus as a son of God, they do not believe in Him as THE Son of God the way we do; in fact, it is only even recently that the Church of Later-Day Saints has begun using the term “Christian” when describing themselves.
Because Mormons do not profess Christ and the Holy Trinity in the same way that the early Church did; because they have reinterpreted both the Old and New Testament to fit their own belief system; because they have forsaken the teachings of the Apostles, Church Fathers, and Nicean Creed; and because they have a whole other book of so-called scripture other than the Bible, the Church of Later-Day Saints can not be truly termed a Christian Church. The Orthodox Church and the Roman Catholic Church both agree that the Mormons are apostates (heretics) and are more of a cult than anything else.
Now this is not to say that Mormons are not moral, nice, or even decent people. They just do not have the true profession of faith as to who Jesus Christ actually is and are thus, far outside the Communion of the Christian Faith.
