Is Mormonism Christian?

Lots of public discussion on this topic, one which I have dealt with for years in my ongoing series of classes on American Heresies.

Kendall Harmon had a great link to this website www.carm.org (Christian Apolegetics and Research Ministry), with a thorough answer.
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Is Mormonism Christian?
"Is Mormonism Christian?" is a very important question. The answer is equally important and simple. No. Mormonism is not Christian. If you are a Mormon, please realize that CARM is not trying to attack you, your character, or the sincerity of your belief. If you are a non-Mormon looking into Mormonism, or if you are a Christian who is simply researching Mormonism, then this paper should be of help to you.
The reason Mormonism is not Christian is because it denies one or more of the essential doctrines of Christianity. Of the essential doctrines (that there is only one God, Jesus is God in flesh, forgiveness of sins is by grace alone, and Jesus rose from the dead physically, the gospel being the death, burial, and resurrection of Jesus), Mormonism denies three of them: how many gods there are, the person of Jesus, and His work of salvation.
Mormonism teaches that God the Father has a body of flesh and bones (D. & C. 130:22) and that Jesus is a creation. It teaches that he was begotten in heaven as one of God’s spirit children (See the Book, Jesus the Christ, by James Talmage, p. 8). This is in strict contrast to the biblical teaching that he is God in flesh (John 1:1, 14), eternal (John 1:1, 2, 15), uncreated, yet born on earth (Col. 1:15), and the creator all (John 1:3; Col. 1;16-17). Jesus cannot be both created and not created at the same time. Though Mormonism teaches that Jesus is god in flesh, it teaches that he is "a" god in flesh, one of three gods that comprise the office of the Trinity (Articles of Faith, by Talmage, pp. 35-40). These three gods are the Father, the Son, and the Holy Ghost. This is in direct contradiction of the biblical doctrine that there is only one God (Isaiah 44:6,8; 45:5). See Trinity for a correct discussion of what the Trinity is.
Because Mormonism denies the biblical truth of who God is, who Jesus is, how forgiveness of sins is attained, and what the gospel is, the Mormon is not Christian -- in spite of all his claims that he is.
Mormonism teaches
Mormon theology teaches that god is only one of countless gods, that he used to be a man on another planet, that he became a god by following the laws and ordinances of that god on that world, and that he brought one of his wives to this world with whom he produces spirit children who then inhabit human bodies at birth. The first spirit child to be born was Jesus. Second was Satan, and then we all followed. But, the Bible says that there is only one God (Isaiah 43:10; 44:6,8; 45:5), that God has eternally been God (Psalm 90:2) -- which means he was never a man on another planet. Since the Bible denies the existence of other gods (and goddesses), the idea that Jesus is the product of a god and goddess couple is rejected. The Bible tells us that Jesus The Jesus of Mormonism is definitely not the same Jesus of the Bible. Therefore, faith in the Mormon Jesus, is faith misplaced because the Mormon Jesus doesn't exist.
Mormonism teaches that the sacrifice of Jesus on the cross itself (and receiving it by faith) is not sufficient to bring forgiveness of sins. It teaches that the forgiveness of sins is obtained though a cooperative effort with God; that is, we must be good and follow the laws and ordinances of the Mormon church in order to obtain forgiveness. Consider James Talmage, a very important Mormon figure who said, "The sectarian dogma of justification by faith alone has exercised an influence for evil," (Articles, p. 432), and "Hence the justice of the scriptural doctrine that salvation comes to the individual only through obedience," (Articles, p. 81). This contradicts the biblical doctrine of the forgiveness of sins by grace through faith (Rom. 5:1; 6:23; Eph. 2:8-9) and the doctrine that works are not part of our salvation but a result of them (Rom. 4:5, James 2:14-18).
To further confuse the matter, Mormonism further states that salvation is twofold. It maintains that salvation is both forgiveness of sins and universal resurrection. So when a Mormon speaks of salvation by grace, he is usually referring to universal resurrection. But the Bible speaks of salvation as the forgiveness of sins, not simple universal resurrection. Where Mormonism states that forgiveness of sins is not by faith alone, the Bible does teaches it is by faith alone. Which is correct? Obviously, it is the Bible.
Mormonism and the Bible
In order to justify its aberrant theology, Mormonism, has undermined the authority and trustworthiness of the Bible. The 8th article of faith from the Mormon Church states, "We believe the Bible to be the word of God as far as it is translated correctly." This means that when the Bible contradicts Mormonism, the Bible isn't trustworthy. The interesting thing is that Joseph Smith allegedly corrected the Bible in what is called The Inspired Version, though it is not used by the LDS church. Though they claim they trust the Bible, in reality they do not. They use Mormon presuppositions to interpret it instead of letting it speak for itself. For example, where the Bible says there are no other gods in the universe (Isaiah 43:10; 44:6,8), they interpret it to mean "no other gods of this world" - which is not what those verses say. They do not trust the Bible and they often state that the Bible is not translated correctly.
Conclusion
Why is Mormonism a non Christian religion? It is not Christian because it denies that there is only one God, denies the true Gospel, adds works to salvation, denies that Jesus is the uncreated creator, distorts the biblical teaching of the atonement, and undermines the authority and reliability of the Bible.
CARM does not deny that Mormons are good people, that they worship "a" god, that they share common words with Christians, that they help their people, and that they do many good things. But that isn't what makes someone Christian. Jesus said in Matthew 7:21-23, " Not everyone who says to Me, 'Lord, Lord,' shall enter the kingdom of heaven, but he who does the will of My Father in heaven. Many will say to Me in that day, 'Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name? And then I will declare to them, 'I never knew you; depart from Me, you who practice lawlessness!" (NKJV). Becoming a Christian does not mean belonging to a church, doing good things, or simply believing in God. Being a Christian means that you have trusted in the true God for salvation, in the True Jesus -- not the brother of the devil, not the god of Mormonism, not the gospel of Mormonism. Mormonism is false and cannot save anyone.