"And if you are in doubt as to that which We have revealed to Our servant, then produce a chapter like it and call on your witnesses (helpers) besides God if you are truthful." (Qur'an, 2:23)

Muslims believe that the Qur'an is the word of God revealed to the Prophet Muhammad and consider the Qur'an as the Prophet's greatest miracle. The following points collectively convince Muslims that the Qur'an and the claim of Muhammad to be the Messenger of God are authentic.

At the time when Qur'an was revealed, poetry in Arabia was developed to exceptionally high standards. People would use poetry in their conversations, debates and fights. Poetry competitions would be organised every year. Acclaimed poems were written in gold and hung on the Ka'bah wall for every one to see. Competent poets would be considered national heroes.

Although Muhammad grew up amongst them, he never worked on poetry or prose. Once the revelation of the Qur'an had commenced, everyone was dazzled by its originality and eloquence, because it neither fell into the category of poetry nor of prose, yet it appeared to have a literary value above all of these. The verse, "You did not read any book before, nor did you write one with your right hand, for then those who say untrue things would have doubted" (Qur'an, 29:48) points to this observation.

Although poetry was developed to a high degree in Arabia in the 7th century, the Arabic language itself was deprived of metaphysical, scientific, scholarly and religious conceptions and expressions. The vocabulary was not civilised. With the Qur'an, the Arabic language gained great value and richness. Its vocabulary reached a level where it included a developed terminology in all areas of study including scientific, economical, social, political, legal and administrative. Muslims consider that such a literary revolution as embodied in the Qur'an could not have come from an illiterate person.

The Qur'an challenges humanity, especially those who do not believe that it is the word of God, to come together and produce not a book, but a single chapter like the ones contained in it. "And if you are in doubt as to that which We have revealed to Our servant, then produce a chapter like it and call on your witnesses (helpers) besides God if you are truthful." (Qur'an, 2:23). Muslims argue that since no one has been able to meet this open challenge it is not humanly possible to produce the Qur'an in its Arabic form.

The Qur'an also argues that if it was the product of a human, there would be many discrepancies and contradictions "...and if it was from any other than God, they would have found in it many discrepancies." (Qur'an, 4:82). Again Muslims argue that since there is no contradictions in the Qur'an even though it was revealed piecemeal over 23 years, it must be the word of God.

The Qur'an predicts that it will be protected in its authenticity since it is the last revealed book of God, "Surely, We have revealed the Qur'an and we will most surely be its guardian." (Qur'an, 15:9). Muslims argue that since this prediction came true and lasted the test of time, then it must be true.

About 332 verses of the Qur'an starts with the address "qul = say!" To Muslims, this unusual feature of starting a sentence gives the impression that what is to be said is being received from another source commanding the Prophet.

There are a number of passages in the Qur'an that speak critically of Muhammad. For example, when he gave permission to some hypocrites from attending an important expedition while everyone joined, the verse "God pardon you! Why did you give them leave until those who spoke the truth had become manifest to you and you had known the liars?" (Qur'an, 9:43) was revealed. On another occasion, because he promised to do something the next day without saying Inshallah (If God pleases), the verse "And do not say of anything: Surely I will do it tomorrow, (say) only if God pleases." (Qur'an, 28:23) was revealed. Such open criticism of the Prophet himself in the Qur'an convinces Muslims that if he was the author he would not include such passages.

Muhammad was never witnessed by his close companions and wives to have studied for the next revelation or prepared himself for an important event subsequent to which substantial new revelation later appeared. This relaxed attitude gives Muslims confidence that Muhammad was not making up the Qur'an himself. He was also not known to have scholarly helpers, on the contrary he was teaching people instead.