The Quranic content is concerned with basic Islamic beliefs including the existence of God and the resurrection. Narratives of the early prophets, ethical and legal subjects, historical events of Muhammad's time, charity and prayer also appear in the Quran. The Quranic verses contain general exhortations regarding right and wrong and historical events are related to outline general moral lessons. Verses pertaining to natural phenomena have been interpreted by Muslims as an indication of the authenticity of the Quranic message.
The central theme of the Quran is monotheism. God is depicted as living, eternal, omniscient and omnipotent (see, e.g., Quran 2:20, 2:29, 2:255). God's omnipotence appears above all in his power to create. He is the creator of everything, of the heavens and the earth and what is between them (see, e.g., Quran 13:16, 50:38, etc.). All human beings are equal in their utter dependence upon God, and their well-being depends upon their acknowledging that fact and living accordingly.
The Quran uses cosmological and contingency arguments in various verses without referring to the terms to prove the existence of God. Therefore, the universe is originated and needs an originator, and whatever exists must have a sufficient cause for its existence. Besides, the design of the universe, is frequently referred to as a point of contemplation: "It is He who has created seven heavens in harmony. You cannot see any fault in God's creation; then look again: Can you see any flaw?"
The doctrine of the last day and eschatology (the final fate of the universe) may be reckoned as the second great doctrine of the Quran. It is estimated that approximately one-third of the Quran is eschatological, dealing with the afterlife in the next world and with the day of judgment at the end of time. There is a reference to the afterlife on most pages of the Quran and belief in the afterlife is often referred to in conjunction with belief in God as in the common expression: "Believe in God and the last day". A number of suras such as 44, 56, 75, 78, 81 and 101 are directly related to the afterlife and its preparations. Some suras indicate the closeness of the event and warn people to be prepared for the imminent day. For instance, the first verses of Sura 22, which deal with the mighty earthquake and the situations of people on that day, represent this style of divine address: "O People! Be respectful to your Lord. The earthquake of the Hour is a mighty thing."
The Quran is often vivid in its depiction of what will happen at the end time. Watt describes the Quranic view of End Time:
- "The climax of history, when the present world comes to an end, is referred to in various ways. It is 'the Day of Judgment,' 'the Last Day,' 'the Day of Resurrection,' or simply 'the Hour.' Less frequently it is 'the Day of Distinction' (when the good are separated from the evil), 'the Day of the Gathering' (of men to the presence of God) or 'the Day of the Meeting' (of men with God). The Hour comes suddenly. It is heralded by a shout, by a thunderclap, or by the blast of a trumpet. A cosmic upheaval then takes place. The mountains dissolve into dust, the seas boil up, the sun is darkened, the stars fall and the sky is rolled up. God appears as Judge, but his presence is hinted at rather than described. [...] The central interest, of course, is in the gathering of all mankind before the Judge. Human beings of all ages, restored to life, join the throng. To the scoffing objection of the unbelievers that former generations had been dead a long time and were now dust and mouldering bones, the reply is that God is nevertheless able to restore them to life."
The Quran does not assert a natural immortality of the human soul, since man's existence is dependent on the will of God: when he wills, he causes man to die; and when he wills, he raises him to life again in a bodily resurrection.
According to the Quran, God communicated with man and made his will known through signs and revelations. Prophets, or 'Messengers of God', received revelations and delivered them to humanity. The message has been identical and for all humankind. "Nothing is said to you that was not said to the messengers before you, that your lord has at his Command forgiveness as well as a most Grievous Penalty." The revelation does not come directly from God to the prophets. Angels acting as God's messengers deliver the divine revelation to them. This comes out in Quran 42:51, in which it is stated: "It is not for any mortal that God should speak to them, except by revelation, or from behind a veil, or by sending a messenger to reveal by his permission whatsoever He will."
Belief is a core aspect of morality in the Quran, and scholars have tried to determine the semantic contents of "belief" and "believer" in the Quran. The ethico-legal concepts and exhortations dealing with righteous conduct are linked to a profound awareness of God, thereby emphasizing the importance of faith, accountability, and the belief in each human's ultimate encounter with God. People are invited to perform acts of charity, especially for the needy. Believers who "spend of their wealth by night and by day, in secret and in public" are promised that they "shall have their reward with their Lord; on them shall be no fear, nor shall they grieve". It also affirms family life by legislating on matters of marriage, divorce, and inheritance. A number of practices, such as usury and gambling, are prohibited. The Quran is one of the fundamental sources of Islamic law (sharia). Some formal religious practices receive significant attention in the Quran including the formal prayers (salat) and fasting in the month of Ramadan. As for the manner in which the prayer is to be conducted, the Quran refers to prostration. The term for charity, zakat, literally means purification. Charity, according to the Quran, is a means of self-purification.