The Quran is the holy scripture of Islam and is considered by Muslims to be the word of God as revealed to the Prophet Muhammad. The traditional Islamic belief is that the Quran was revealed to Muhammad by God through the angel Gabriel, and that it was written down by Muhammad's companions during his lifetime. This belief is supported by the historical evidence and the text of the Quran itself, which claims to be the word of God revealed to a prophet.
However, there are alternative theories about the authorship of the Quran that suggest it may have been a collaborative work or written by multiple authors over a period of time. These theories are based on linguistic and stylistic analysis of the text, as well as historical and archaeological evidence.
One argument for multiple authorship is that there are variations in style and language throughout the Quran, which some scholars argue suggest that the text was written by different authors at different times, rather than by one single author. Additionally, certain verses in the Quran contain information that would have been unlikely to have been known by the Prophet Muhammad, but would have been known to people who lived after his time. This has led some scholars to suggest that these verses were added to the text by later editors.
On the other hand, traditional Islamic scholarship argues that the variations in style and language can be explained by the context in which the verses were revealed and that the Quran's text has been preserved in its original form since its revelation. They argue that the Quran is the direct word of God, revealed to the Prophet Muhammad, and that the Prophet's companions wrote it down as it was revealed.
The question of the authorship of the Quran is an ongoing area of debate and research among scholars. Ultimately, the belief in the Quran's divine origin is a matter of faith for Muslims.