Islam

Islam falls squarely within the tradition of Abrahamic monotheism and shares certain parallels with both Judaism and Christianity. As explained above, the three major sectarian divisions among Muslims did not originate in doctrinal disagreements. Although certain doctrinal differences among them developed over time, these do not affect essential core beliefs, which are shared universally by Muslims.

At the heart of Islamic theology lies an uncompromising and absolute belief in the unity of God, whom Muslim and Christian speakers of Arabic alike refer to as Allah. The Islamic doctrine of the oneness of God, referred to as tawhid in Arabic, forms the first half of the Muslim profession of faith: "There is no god, but God." The Koran is quite specific in its rejection of the Christian doctrine of the Incarnation, and Muslim theologians have traditionally shared the skepticism of their Jewish colleagues about the genuineness of Christian monotheism.

To associate anything else with God, or to submit to anything other than God, is shirk (polytheism), the one sin that God does not forgive. Idolatry in the Muslim understanding involves far more than worshiping pagan deities, and shirk occurs whenever people place their own personal desires above the will of God.

The God of Koranic revelation is, like the God of the Hebrew Bible, both the creator of the universe and the ultimate judge before whom all people will eventually be called to account at the end of time. These dual qualities of creator and judge help to explain why the Koran stresses both God's mercy and wrath.

Muslim theologians distinguish between the transcendent essence of divinity, which is unknowable, and the attributes of God, which are manifest in the cosmos. In discussing these divine attributes, classical Muslim theologians usually referred to the "Beautiful Names of God." Although the attributes, or names, of God are frequently paired in contrasting qualities (e.g., "He who gives life" and "He who brings death"), the "names of mercy" are said to dominate the contradictory "names of wrath."

Having created the universe, God ordains an order or law according to which all things rightfully submit. Submission to the will of God, in fact, is central to veneration of the divine—in which the entire created cosmos is properly engaged. Ironically, humanity, which stands at the apex of the created universe, is almost uniquely endowed with the capacity to something less than full submission to God's will. Like Jews and Christians, Muslims believe that humanity comprises a very special part of creation, being created in the image or "form" of God. This unique attribute of human beings affords humanity the possibility of realizing its noble calling—serving as God's deputies on earth (khalifat allah fi'l-ard). Because human beings possess the ability throughout their lives to submit to things other than God, it is on the sincere extent of his submission that each person will be judged by God at the end of days. The awesome and inescapable reality of Judgment itself is dealt with in great detail in the Koran, as are the alternative destinations of paradise and hell to which the judged are ultimately consigned.

The ultimate sign of God's mercy is the fact of divine guidance, which has come to humanity through the agency of prophets (anbiya', singular nabi). Beginning with the first man, Adam, and concluding with Muhammad, God has sent prophets bearing revelation outlining the divine will for mankind. Unfortunately, the human capacity for ignoring and twisting the revelations of God is limitless, which necessitates God's correcting and restating revelation by sending subsequent prophets. With Muhammad and the Koran, however, Muslims believe, humanity has the corrected and most complete version of God's revealed word. And assertion of the prophetic role of Muhammad forms the second half of the Muslim profession of faith. The Koran reflects God's considerable impatience with the human capacity to corrupt the divine message, which is underscored by warnings that God's patience in this regard is at an end, and hence there will be no further divine revelation. Muhammad, therefore, is understood as the "seal of the prophets."

The Koran, as the complete and perfected word of God, made manifest in the world through the prophetic agency of Muhammad, is the earthly version of a heavenly archetype existing eternally with God. It must be emphasized here that Muslims understand the Koran not as the word of Muhammad, somehow inspired by God, but as the absolute word of God himself. In this sense, Muslims see Islam as "the religion of the Book." They likewise regard Jews and Christians as "people of the Book," because they are believed to have also received genuine, though incomplete, divine revelation. The actual content of both the Hebrew Bible and the Christian New Testament, however, have historically held very little interest for Muslims because not only are they incomplete, but Muslims believe that Jews and Christians either willfully or carelessly corrupted the content of the divine scripture they received.

The fact that Christians and Jews were recipients of genuine revelation, however, has historically implied for Muslims that neither Jews nor Christians could be forcibly converted to Islam. This same prohibition against forcible conversion was later applied to various other religious communities that Muslims identified as genuinely monotheistic. Polytheists, however, did not fare so well, and were forcibly converted, on pain of death or enslavement, particularly in the early Islamic period.

Although Christians, Jews, and other monotheists, referred to collectively as dhimmis, or "protected peoples," were not routinely compelled to convert to Islam, they were frequently subjected to various disabilities, such as the payment of a special tax known as the jizya, and indignities, such as sumptuary laws, designed to encourage their conversion to Islam. Although this limited tolerance that medieval Muslim societies traditionally afforded other monotheistic faiths would not satisfy contemporary sensibilities, by comparison with such institutions as the Inquisition in Christian Europe, Islamic tolerance of other monotheistic faiths was indeed remarkable.

The refusal of Christians and Jews to recognize the prophecy of Muhammad was viewed by Muslims as willful disobedience of God, which should not be ignored but actively challenged. This sense of responsibility for the fate of the souls of others was very much part of a larger understanding Muslims traditionally had, that they were specifically commanded by God to "command what is good, and forbid what is evil" in the world. Muslims in the classical period suffered no doubts about the answer to Cain's rhetorical question in the Book of Genesis: they clearly understood that they were indeed their brother's keeper.

The word Islam itself in Arabic conveys a notion of inner peace that humans can only achieve through sincere submission to the will of God. The most obvious demonstration of this submission to God is expressed in what are frequently referred to as the five pillars of Islamic faith: devout and public profession of faith (shihada), the ritual performance of worshipful prayer (salat) at five appointed times each day, the annual giving of alms to the poor (zakat), annual fasting (sawm) from before sunrise until sunset throughout the Islamic month of Ramadan, and the performance of a pilgrimage (hajj) to Mecca at least once during one's life, assuming health and finances permit. It must be stressed, however, that these ritual obligations only demarcate the most basic outlines of submission to God's will. Devout Muslims see themselves as engaged in a profound struggle to submit their own wills to God's law in every aspect of life. In fact, they frequently refer to this inner struggle as the greater jihad.