Reading the results of the Pew poll about Mormonism, reminds me of what Martin Luther King Jr. wrote in "Strength to Love": "Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity."
The fact that two thirds of mainline Protestants and Catholics believe Mormonism is a Christian religion is an unfortunate example of both.
The Mormon faith is not the same as the Christian faith. Examples abound. Consider these few.
The Ministry of Jesus
In the 2 Nephi 5:21, in the Book of Mormon, in 600 B.C., Lehi, a Jewish prophet from the tribe of Manassah, left Jerusalem with several others, sailed east and landed in South America. Two of Lehi's sons, Lamen and Lemuel, rebelled against God. God cursed them and gave them dark skin -- birthing the Native American race. In 2 Nephi 12:3-12, in A.D. 34, Jesus Christ descended from heaven, baptized the Native Americans, called and commissioned 12 disciples, instituted sacraments, and taught the message of the Sermon on the Mount.
According to the first four gospels of the Bible, Jesus Christ lived and ministered in the region of modern-day Israel. He never appeared in the Americas.
The Virgin Birth
The Mormon Church teaches that Mary, the mother of Jesus, conceived Jesus through sexual relations with God the father. Brigham Young wrote in the Journal of Discourses 8:115, "The birth of the Savior was as natural as are the births of our children; it was the result of natural action. He partook of flesh and blood -- was begotten of his Father, as we were of our fathers." Likewise, the Mormon Apostle Bruce McConkie wrote, "Christ was begotten by an Immortal Father in the same way mortal men are begotten by mortal fathers" (Mormon Doctrine, 1966, pg. 547; Read also, The Seer, by Orsen Pratt; Doctrines of Salvation Vol. 1; or The Teachings of Ezra Taft Benson).
The Bible teaches that Mary, a virgin, "was found to be with child through the Holy Spirit" (Matthew 1:18). It is a miracle that is difficult for many to understand, but not one that occurred as a result of Mary having intercourse with a human or a spiritual being.
The Spirit World
Mormons believe that God, angels and humans are the same. BYU religion professor Robert Millet clarifies this concept in "The Mormon Faith: A New Look at Christianity" (1998, pg. 39): "Latter-day Saints believe that angels are men and women, human beings, sons and daughters of God, personages of the same type as we are. Parley P. Pratt, an early apostle wrote, 'Gods, angels and men are all of one species, one race, one great family.'"
Additionally, angels are created through sexual relations, better known as "celestial exaltation" between God and his heavenly wife in the spirit world. In the LDS Church manual, Achieving a Celestial Marriage, celestial exaltation "includes the ability to procreate the family unit throughout eternity. This our Father in heaven has power to do. His marriage partner is our mother in heaven. We are their spirit children, born to them in the bonds of celestial marriage."
Spirits are gender specific, immortal and eternal: "Each [male and female] is a beloved spirit son or daughter of heavenly parents, and, as such, each has a divine nature and destiny. Gender is an essential characteristic of individual premortal, mortal, and eternal identity and purpose" ("The Family: A Proclamation to the World," issued by the First Presidency and the Twelve Apostles of the LDS Church, 1995).
Brigham Young stated:
Mankind are organized of element designed to endure to all eternity; it never had a beginning and never can have an end. There never was a time when this matter, of which you and I are composed, was not in existence, and there never can be a time when it will pass out of existence; it cannot be annihilated.
It is brought together, organized, and capacitated to receive knowledge and intelligence, to be enthroned in glory, to be made angels, Gods -- beings who will hold control over the elements, and have power by their word to command the creation and redemption of worlds, or to extinguish suns by their breath, and disorganize worlds, hurling them back into their chaotic state. This is what you and I are created for. (Discourses of Brigham Young, p. 48; see also Doctrines and Covenants 93:29-33)
The Bible teaches that angels (immortals) and humans (mortals) are to worship God (the sole eternal being) their creator (Hebrews 1). Angels have taken on anthropomorphic characteristics but they are not human. They bore messages to humans from God (Matthew 1:20; Luke 1:11, 26, 2:9; Acts 8:26) and assisted Jesus (Matthew 26:53; Luke 22:43) and his people (Psalm 91:11, 12; Acts 5:19; Hebrews 1:14).
Jesus and Satan
The Mormon church explicitly teaches in the Pearl of Great Price in both the books of Moses (chapter 4) and Abraham (chapter 3) that Jesus Christ and Satan are both sons of God and are not only spirit brothers to each other but are spirit brothers to humans and angels as well. Brigham Young referred to "the Devil, the mighty Lucifer, the great prince of the angels, and the brother of Jesus" in the Journal of Discourses 6:207. In an Ensign magazine (a publication of the Mormon church) answer to a question from a reader, "How can Jesus and Lucifer be spirit brothers when their characters and purposes are so utterly opposed?" the magazine stated, "On first hearing, the doctrine that Lucifer and our Lord, Jesus Christ, are brothers may seem surprising to some--especially to those unacquainted with latter-day revelations. But both the scriptures and the prophets affirm that Jesus Christ and Lucifer are indeed offspring of our Heavenly Father and, therefore, spirit brothers....But as the Firstborn of the Father, Jesus was Lucifer's older brother" (1986, pg. 25).
The Bible teaches that God has only one son, Jesus Christ (John 3:16, 17) who came to destroy the work of the devil (I John 3:8).
Both Mormonism and Christianity make very different truth claims.
Christians must know what they say they believe otherwise their claim to faith is meaningless.