I. The Prophets
Both Joseph Smith and Muhammad claimed the role of Prophet. Each saw themselves, and were seen by their followers, as being in the line of the great Jewish prophets like Noah, Moses, Ishmael, and Isaac. The Koran names Jesus of Nazareth as a prophet. The Mormon view of Jesus will be discussed below. It is notable that during his lifetime his followers referred to Joseph Smith, in writing, as The Prophet, which was how Muhammad has always been referred to by the Islamic faithful.
The Koran (or Quran) says at 4:163-165:
163 Lo! We inspire thee (Muhammad) as We inspired Noah and the prophets after him, as We inspired Abraham and Ishmael and Isaac and Jacob and the tribes, and Jesus and Job and Jonah and Aaron and Solomon, and as we imparted unto David the Psalms;II. Polygamy
164 And messengers We have mentioned unto thee before and messengers We have not mentioned unto thee; and Allah spake directly unto Moses;
165 Messengers of good cheer and of warning, in order that mankind might have no argument against Allah after the messengers. Allah was ever Mighty, Wise.
The Koran says limits polygamous marriage to four wives [4:3]:
... marry other women of your choice: two, three, or four. But if you fear that you will not be able to maintain justice between your wives, then marry only one.Joseph Smith endorsed unlimited polygamy. According to former church members writing in 1844 shortly before Smith died, he and other church elders recruited maidens from Europe, who arriving in the United States were deflowered and given no choice except to become one of many wives.
The two largest modern Mormon denominations now both officially rejected polygamy in order to avoid further prosecution for a practice that was unlawful in the United States. However, fundamentalist Mormon sects still practice polygamy, reports of its being practiced in secret by mainstream Mormons have been abundant, and it is hard to reconcile monogamy with Joseph Smith's status as The Prophet. In fact in the Doctrine and Covenants any man aspiring to priesthood is encouraged to take multiple wives [D&C 132:61-62]:
61. And again, as pertaining to the law of the priesthood—if any man espouse a virgin, and desire to espouse another, and the first give her consent, if he espouse the second, and they are virgins, and have vowed to no other man, then is he justified.The emphasis on the virginity of multiple wives is why teenage women have been the main target of Mormon missionaries from the time of Joseph Smith until the present. Joseph Smith is reputed to have had over thirty wives at the time of his death in 1844.
III. Rejection of Jesus Christ as the One True God
Muhammad lived from 570 to 632 A.D. At this time the orthodox Christian church (only later splitting into Roman Catholic and Eastern Orthodox branches) had dominated the people's around the Mediterranean for over two centuries. Yet many Jewish and non-orthodox Christian communities still had not been stamped out, and in Arabia itself various forms of pagan worship survived.
While given as a revealed truth from Allah, Muhammad's belief that Jesus of Nazareth was a prophet, not a resurrected god, was supported by historical evidence. Jews in the area, of course, rejected Jesus as both God and Messiah. More important were the Christian Jews whose religion was in line with the original teachings of Jesus. Their historic memory was that Jesus did not claim to be God and was not resurrected after crucifixion. Those ideas were formed decades after Jesus's death, as is reflected in the differences between the Gospels of Matthew, Mark and Luke, in which Jesus does not claim divinity, and in John, where he makes it very clear he thinks he is one with God.
Muhammad, in the Koran, quotes Jesus against the Christians, avoiding the Gospel of John and instead interpreting Jesus as having said there is only one, undivided God, Allah, and that no man could be God. Which is the position of Islam.
Despite his demotion to Prophet, Jesus (Isa) and his mother, Mary (Maryam) play a major role in the Koran, even aside from preaching against Christianity.
As with Islam, which developed over the course of the life of Muhammad, the relationship of the Latter Day Saints to Jesus of Nazareth is complicated by the temporal development of the revelations of Joseph Smith. In the Book of Mormon Jesus is pretty much the Jesus of the Christians except, unbeknownst to them, after his Ascension Jesus is said to have visited the Americas.
Later, as the power of being himself treated as a Prophet and having a lot of young wives went to his head, Joseph Smith deviated increasingly from Christian doctrine in his Doctrine and Covenants. While not explicitly rejecting the Trinity, Joseph Smith described an elaborate cosmology which would allow him and his male followers to become godlike, and Jesus-like, themselves. Even God the Father, our planetary god, was reduced to an advanced and glorified man. Quoting those who left the church just before Smith's death [Nauvoo Expositor, June 7, 1844]:
"Among the many items of false doctrine that are taught the Church, is the doctrine of many Gods, one of the most direful in its effects that has characterized the world for many centuries ... It is contended that there are innumerable Gods as much above the God that presides over this universe, as he is above us; and if he varies from the law unto which he is subjected, he, with all his creatures, will be cast down as was Lucifer."IV. Rejection of alcohol
While it may seem to be only of practical importance, the rejection of alcohol by Islam, and later by Joseph Smith and his followers, is of the deepest symbolic and theological importance.
Wine plays a role in two key sacraments of Christianity, marriage and communion. Jesus is believed by Christians to have turned water into wine at the wedding feast of Cana [Bible, John 2:1-11], his first miracle in John (but missing from the three earlier gospels).
By rejecting wine both Muhammad and Joseph Smith rejected the Christian rule of monogamy. They also both recognized divorce, which Jesus outlaws for Christians in Matthew 19:3-9.
According to his followers, Jesus is not a Prophet, or the Messiah, but a true, resurrected God. Wine represented, in his times, the transubstantiation from of an ordinary food, the grape, into an intoxicant. Earlier religions in which a man-god was killed or sacrificed and then rose from the dead, showing the glory of God, were closely tied to celebrating events with wine. Notably the Greek god Dionysus and the Egyptian god Osiris had large cult followings throughout the Roman Empire that had many doctrines that were adopted by non-Jewish Christians at some point in the history of the early Church.
By rejecting the drinking of alcoholic beverages, Joseph Smith brought his church more closely to conformity with orthodox Islam and differentiated it from orthodox Christianity.
"That inasmuch as any man drinketh wine or strong drink among you, behold it is not good." [Doctrine and Covenants. 89:5 by Joseph Smith the Prophet at Kirtland, Ohio, February 27, 1833]
"Satan desires to stir up enmity and hatred between you with intoxicants and gambling, to prevent you from the remembrance of Allah and prayers. Will you not abstain?" [Muhammad the Prophet, Koran, 5:91]