To determine whether some one or group is Christian, we must go to the original source that defines what being a Christian is. That is the holy Bible. Jesus taught his followers, "I am the way, the truth and the life. No one comes to the Father, except through Me" (Jn 14:6). The doctor Luke tells us in Acts, under the inspiration of the Holy Spirit, "And there is salvation in no one else, for there is no other name under heaven given among men by which we must be saved" (Acts 4:12).
And in fact, Mormons, and other groups I'm sure, will confess this truth also. So what sets apart the orthodox, Evangelical Christian? This is where we examine the presuppositional ideas and understanding of the parties in question.
First off, what does the Bible teach? Now the answer to this question could make up a semester long seminary course. Clearly, there is not space for this, so we will narrow the question to the most important figure, and conerstone of the Christian faith: Jesus of Nazareth (Mt. 2:23). Jesus, the Bible teaches, is the only begotten Son of the Living God (Jn. 3:16, 20:31; 1 Cor. 1:9; 1 Jn. 1:3), that he is equal, co-eternal with God the Father. (Rom 1:3-4; Rev 1:7-8, 22:13), and that He was born of the Holy Spirit (Is. 7:14; Lk. 1:35). Jesus Christ, through his death and suffering of crucifixion on the cross, would be the propitiation (atoning sacrifice) of our sins, and provide justification for the many (Ps. 22:16; Is. 53:5-11; Jn. 1:29; Mt. 26:2; Jn. 13:1). The scriptures teach, as cited above, that salvation is through faith only in his name, by grace (Eph. 2:8,9; Jn. 14:6; Acts 4:12). After the sending of the Holy Spirit, at the Jewish feast of Pentecost (instituted in Lev. 23), who inspired the apostles in the writing of the New Testament, the Bible teaches revelation was sealed, finito (Heb. 1:2).
The Mormon faith teaches that Jesus is the spiritual firstborn son of God, and spirit brother to every other human and angel (including Satan/Lucifer). Since Mormons do not believe in the Trinity as claimed by the Biblical faith, Mormonism teaches that God the Father came down and had sex with the virgin Mary to impregnate her with Jesus. It teaches that life on earth is a school or test, if you will, for the spirit children of God to attain to their own state of god-hood. Yes, the goal of Mormons is to be god, of their own planet with their own spirit children (born of their goddess wife/wives). "As man is, God once was. As God is, man can become." http://www.leaderu.com/orgs/probe/docs/mormon1.html
Mormons believe do not hold that revelation was closed with the person of Jesus Christ. They believe in a progressive revelation, as do the New Apostolic Reformation, of which Gov. Perry joined with in organizing and facilitating The Response fasting and prayer rally. And Mormons, as the NAR prophets and pastors, believe in the mandate of "taking back" America in the name of their religion. http://www.wbur.org/npr/140946482/apostolic-leader-weighs-religions-role-in-politics
The Mormons have a "white horse" prophecy of the nation being rescued by a Mormon coming to office as president and restoring the nation, with all the people apologizing and giving gratitude to the Mormons for rescuing the nation, and restoring us to our "divinely-inspired" US Consitution. The Bible teaches that the world will come under the control of a one-world leader, a one-world government (Dan. 7:23) which will be under his control for seven years (Dan. 9:27), but then the Messiah will return to set up his rightful rule, for one thousand years (Zech 14:9), before Satan is let loose again to deceive the nations (Rev. 20:7,8). Then the world will be destroyed by fire (2 Ptr. 3:7) and the great judgment, and then all things will be made new. After this, the redeemed, those who were born-again will live upon earth with God and serve the LORD and live in a paradise forevermore (Rev. 21:1, 5).
The holy Bible teaches that salvation is "by grace, through faith, and that not of yourselves. It is the gift of God, not of works, lest any man should boast" (Eph 2:8,9). The Mormon book of 2 Nephi states "for we know that it is by grace that we are saved, after all we can do." 2 Nephi 25:23 http://www.mrm.org/2-nephi-25-23. It sounds very close to what the Bible teaches, but adds a almost subtle difference, "after all we can do." That changes the whole game and puts Mormonism into the category of salvation-by-works, like every other world religion except for Christianity, which states, "it is the gift of God, not of works, lest no man should boast."
One well known so-called evangelical (or wolf in sheep's clothing) leader recently said that Mitt Romney is an "outstanding Christian." Really? Doesn't that fly in the face of what the Bible says of the elect? How could an "outstanding" evangelical leader make such an error? The apostle Paul, former murderer and persecutor of the church, wrote: "But even if we, or an angel from heaven, were to preach to you a gospel contrary to what we have preached to you, let him be anathema (eternally accursed)" Gal. 1:8.
Clearly Joseph Smith didn't have this verse in mind when the angel of light (2 Cor. 11:14) appeared to him and taught him the "true" gospel.