As with other prophets and messengers, God supported Muhammad by allowing him to work miracles and thus prove that he was a genuine prophet. The singular miracle of Muhammad and the ultimate proof of the truthfulness of Islam is the Qur'an. In accordance with the words of the scripture itself, Muslims believe that the Qur'an is the timeless word of God, "the like of which no human can produce." This trait of the scripture, called inimitability (i'jaz), is based on belief in the divine authorship of the Qur'an. Unlike earlier religions, the miracle of Islam is a literary miracle, and Muhammad's other supernatural acts are subordinate to it.
This belief in the unique nature of the Qur'an has led Muslims to devote great intellectual energies to the study of its contents and form. In addition to interpreting the scripture and deriving doctrines and laws from it, many disciplines within Qur'anic studies seek to understand its linguistic and literary qualities as an expression of its divine origins.
The Qur'an is made up of 114 chapters, called suras, which are roughly organized, from the second chapter onward, in order of length, beginning with the longest and ending with the shortest chapters.
The first chapter, al-Fatiha ("the Opening"), is a short chapter that is recited during each of the five daily prayers and in many other ritual prayers. All but one chapter begin with the formula "in the name of God, the Merciful Lord of Mercy" (bism Allah al-Rahman al-Rahim). Each chapter is divided into verses called ayat (singular aya, meaning "sign" or "proof"). With few exceptions the verses are randomly organized without a coherent narrative thread.
A typical chapter of the Qur'an may address any combination of the following themes: God and creation, prophets and messengers from Adam to Jesus, Muhammad as a preacher and as a ruler, Islam as a faith and as a code of life, disbelief, human responsibility and judgment, and society and law. Later Muslim scholars have argued that the text's timelessness and universality explain the lack of narrative coherence and the randomness of the topics. In other words, the multiple meanings of the Qur'an transcend linear narrative as they transcend any particular historical moment.
Islam recognizes the divine origins of the earlier Hebrew and Christian Scriptures and represents itself as both a restoration and a continuation of their traditions. Because of this, the Qur'an draws on biblical stories and repeats many biblical themes. In particular, the stories of several biblical prophets appear in the Qur'an, some in a condensed form; other stories, such as those of Abraham, Moses, and Jesus, are given in elaborate detail and even with subtle revisions of the biblical accounts.
One of the important differences between the Qur'anic and biblical stories of Abraham's sacrifice of his son, for example, is that the Qur'an suggests this son is Ishmael, from whom Arabs are descended, and not Isaac, from whom the tribes of Israel are descended. A more substantial difference relates to the Islamic story of Jesus, who according to the Qur'an is a mortal, human prophet. The Islamic faith categorically rejects the idea that God was ever born, as opposed to Christian belief that Jesus was born the son of God. Islam also rejects the idea that God shared his divinity with any other being.
Another important idea elaborated in the Qur'an and later Islamic doctrine, in conscious distinction from the biblical accounts, is that although prophets are capable of human errors, God protects them from committing sins and also protects them from excruciating suffering or humiliating experiences. God would not abandon his prophets in times of distress. Therefore, the Qur'an maintains that God interfered to save Jesus from torture and death by lifting him to heaven and replacing him on the cross with someone who looked like him.
From its inception during the lifetime of Muhammad, Islamic doctrine gave priority to the preservation of the scripture. As a result, one of the earliest expressions of religiosity focused on studying, reciting, and writing down the scripture. When Muhammad died, the preservation of the scripture was also a conscious concern among his companions and successors. Early historical sources refer to immediate efforts undertaken by successors of Muhammad to collect the chapters of the Qur'an, which were written down by his various companions.
Within about two decades after the death of the Prophet, various existing copies of parts of the Qur'an were collected and collated by a committee of close companions of Muhammad who were known for their knowledge of the Qur'an. This committee was commissioned by the third successor of Muhammad, Uthman ibn Affan, and the committee's systematic effort is the basis of the codified official text currently used by Muslims. The thematic randomness of the verses and chapters of the Qur'an in its current format clearly illustrates that the early companions who produced this official version of the Qur'an were primarily concerned with establishing the text and made no attempt to edit its contents in order to produce a coherent narrative. Because of this, scholars agree that the Uthmanic text genuinely reflects, both in its content and form, the message that Muhammad preached.
Despite the consensus among Muslims on the authenticity of the current format of the Qur'an, they agree that many words in the Qur'an can be interpreted in equally valid ways. The Arabic language, like other Semitic languages, has consonants and vowels, and the meanings of words are derived from both. For several centuries, the written texts of the Qur'an showed only the consonants, without indicating the vowel marks. As a result, there are different ways in which many words can be vocalized, with different meanings; this allows for various legitimate interpretations of the Qur'an.
One of the disciplines for the study of the Qur'an is exclusively dedicated to the study and documentation of acceptable and unacceptable variant readings. According to Muslim scholars, there are some 40 possible readings of the Qur'an, of which 7 to 14 are legitimate. The legitimacy of different possible interpretations of the scripture is supported by a statement in the Qur'an that describes verses as either unambiguously clear, or as ambiguous because they carry a meaning known only to God. Therefore, with the exception of a small number of unquestionably clear injunctions, the meaning of the Qur'anic verses is not always final.
The Qur'an is the primary source of authority, law and theology, and identity in Islam. However, in many cases it is either completely silent on important Islamic beliefs and practices or it gives only general guidelines without elaboration. This is true of some of the most basic religious obligations such as prayer, which the Qur'an prescribes without details. Details elaborating on the teachings and laws of the Qur'an are derived from the sunna, the example set by Muhammad's life, and in particular from hadith, the body of sayings and practices attributed to him.