Monotheism is the essence of Islam. It is the affirmation of believing that there is no other divinity other than Allah. For the most part, the spirit of the Quran revolves around the theme of pure monotheism. Thus, God is the center of a Muslim's belief. Whereas certain religions focus on individuals, for example, Christianity's focus on Jesus Christ, Islam focuses solely on God. Islam is based on the Absolute (God), not His manifestations. The Quran itself speaks of the oneness of God:
Allah has borne witness that there is no Allah but Him, and the angels, and those with knowledge also witness this. He is always standing firm on justice. There is no Allah but Him, the Mighty, the Wise (3:18).
The oneness of God is not only a philosophical argument, but also an affirmation in which all human beings once declared the oneness of God before their souls entered the body:
[Remember] when your Lord brought forth the children of Adam from their loins and made them testify over themselves, saying, “Am I not your Lord?” They said, “Yes! We testify,” lest you should say on the Day of Resurrection, “Verily, we were unaware of this” (7:172).
At that time, every person to be created proclaimed God's majesty, sovereignty, power, transcendence, and absolute oneness. Such was the covenant God made with all people at the time of their creation, whether people presently claim to believe in God or not. Similarly, all people today, regardless of origin, are naturally inclined toward the idea that God is one and without a partner. The Quran informs the Prophet Muhammad of the following:
Set your face to the true religion [Islamic monotheism], the natural inclination [fitra] with which Allah has created mankind. [Let there be] no change in what Allah has made; that is the straight religion, but most people do not understand (30:30).
One of the shortest chapters in the Quran, “The Oneness of Allah,“1 summarizes the nature of God in five verses:
In the name of Allah, the Infinitely Compassionate, the Most Merciful: Say, 'He is Allah, the One Allah, the Eternal Originator, He does not bear children, nor was He born and He is beyond compare.'
The most fundamental Islamic teachings about God are contained in the previous verses; there is only one God, He is eternal, unique, and has no kinship, creator, or resemblance to any human being. Prophets have stated some of the divine attributes of God.
Prophet Abraham said, “My Lord is He who gives life and causes death” (2:258). When confronting Pharaoh, Moses said, “Our Lord is He Who gave each thing its form and nature then guided it aright” (20:50). The two verses describe God in His relation to human beings; however, God's being extends far beyond His relation to humankind. Imam Ali described God in the following manner:
He who assigns to Him different conditions does not believe in His oneness, nor does he who likens Him grasp His reality. He who illustrates Him does not signify Him; he who points at Him and imagines Him does not mean Him. Everything that is known through itself has been created, and everything that exists by virtue of other things is the effect of a cause. He works but, not with the help of instruments; He fixes measures, but not with the activities of thinking; He is rich, but not by acquisition. Time does not keep company with Him, and implements do not help Him.
His being precedes time, His existence precedes non-existence, and His eternity precedes beginning. By His creating the senses, it is known that He has no senses. By the contraries in various matters, it is known that He has no contrary, and by the similarity between things it is known that there is nothing similar to Him. He has made light the contrary of darkness, brightness that of gloom, dryness that of moisture, and heat that of cold.
He produces affection among inimical things…He is not confined by limits nor counted by numbers. Material parts can surround things of their own kind, and organs can point out things similar to themselves…Through them, the Creator manifests Himself to the intelligence, and through them He is guarded from the sight of the eyes…He has not begotten anyone lest He be regarded as having been born. He has not been begotten; otherwise, He would be contained within limits. He is too high to have sons…Understanding cannot think of Him so as to give Him shape…2
God expresses His own eternity and perpetuity in the Quran when He states that, “Every thing on earth shall perish, but the face of Allah will remain, full of majesty and honor” (55:26-27).
And to Allah belong the most beautiful names, so call on Him by them (7:180). Islamic tradition states that God has many different names representing different aspects of His being; ninety-nine are known commonly among Muslims.
The emergence of Islam returned Abrahamic monotheism to its original purity. Islam perceives the doctrine of trinity and incarnation as a veil cast upon the complete reality of divine unity. Nothing should compromise divine unity. God is the absolute, the one without condition, and above all relations. The distinguishable feature of Islamic faith from other monotheistic religions is its insistence on absolute monotheism. Islam entirely opposes any association concerning God. This includes the exclusion of the idea that Jesus, the Messenger of God, was God himself. God states in the Quran:
It is not for a man, that Allah should give him [Jesus] the Book [Gospel], and Judgment, and apostleship, and yet he [Jesus] should say to people, “Be ye worshippers of me, besides Allah's,” but rather [he would say] “Be ye Allah what ye teach the Book and what ye read [yourselves]” (3:79).3
Muslims believe that Jesus was a human prophet and divinely inspired by God. However, Jesus is considered to be a servant and conveyer of God's message. Neither the Old Testament nor the New Testament mentions that Jesus was the son of God. Barbara Brown, a contemporary American scholar, supports this idea with the following statement:
The doctrine of divinity states that Jesus is the Son of God, the Word of God made flesh. Even though Jesus himself never claimed to be divine, Paul gave him this attribute for one reason —to gain converts among the Gentiles. The Gentiles were pagans who were used to worshipping gods that had wonderful legends and myths behind them. Several of the pagan deities of the time such as Mithras, Adonis, Attis, and Osiris were all the offspring of a supreme ruling idol, and each had died a violent death at a young age, coming back to life a short time later in order to save their people. Paul took this into account, giving the pagans something similar in Christianity. He attributed divinity to Jesus, saying he was the Son of God, the Supreme, and that he too had died for their sins. In doing so, Paul compromised the teaching of Jesus with pagan beliefs in order to make Christianity more acceptable to the Gentiles.
The term “son of God” was not something new. However, it had been used in the Old Testament to refer to David (Saul 2:7) and his son Solomon (I Chronicles 22:100) and to refer to Adam (Luke 3:38) in the New Testament. In his famous Sermon on the Mount, detailed in Matthew 5, Jesus tells his listeners, “Blessed are the peacemakers, for they shall be called sons of God.” In all cases, the term “son of God” was not meant to be applied literally but to signify love and affection from God to the righteous. “Son of God” means a special closeness to God, not to be of God. After all, people are sons [spiritual dependants] of God, and God is the creator of all life.4
Christians who lived during the time of Jesus believed that Jesus was divinely inspired by God, not God himself. However, after the ascension of Jesus to heaven, Saint Paul, who was deeply influenced by Roman paganism, wanted his preaching of Christianity to be more appealing to the Gentiles; thus, he compromised the teachings of Jesus by adopting certain pagan ideas and interpolating them into Christianity. Even though it was not part of the original teachings of Jesus, the idea of the trinity spread.