This verse acts as a "functional definition" of the Quran's purpose. It traps the narrative by making the Quran dependent on the "clear proofs" of the past.
Surah 16:44:
With clear proofs and writings; and We have revealed unto thee the Remembrance that thou mayst explain to mankind that which hath been revealed for them, and that they may perchance reflect."
The verse refers to the previous messengers as coming with bil-bayyināti wa-zuburi ("clear proofs and writings/scriptures").
The Quran calls the previous scriptures "clear proofs." In logic, a "clear proof" is a piece of evidence that is unmistakable and certain.
If the Torah and Gospel were corrupted, they would no longer be "clear proofs"—they would be "dark deceptions." By labeling them as clear proofs, the Quran endorses the integrity and clarity of the scriptures held by the people at that time (the 7th century).
The verse states that the Quran was revealed so that Muhammad could li-tubayyina ("explain" or "make clear") what was already revealed for mankind.
An "explanation" makes an existing text easier to understand; it does NOT change the fundamental facts of the original text.
If the original text (the Bible) says Jesus is the Son of God who died for sins, and the "explanation" (the Quran) says He is not the Son and did not die, then the Quran isn't explaining the previous revelation—it is negating it. A "clarification" that says the original was 180 degrees wrong is actually a contradiction.
The phrase "that which hath been revealed for them" (mā nuzzila ilayhim) refers to the revelation currently in the possession of the people.
This anchors the Quran to the historical manuscripts of the 7th century. The Quran’s job was to explain the books the Jews and Christians were already reading.
Since the 7th-century manuscripts (the Bible) are the same as our modern ones, the Quran’s mission was to "explain" a book that explicitly teaches the Trinity and the Atonement. If the Quran fails to "explain" those concepts and instead denies them, it has failed its own divine mandate as defined in 16:44.
Surah 16:44 says the Quran was revealed to explain the previous scriptures which were 'clear proofs.'
If I have a 'clear proof' (the Gospel) that says Jesus is God, and you come to 'explain' it by saying He is NOT God, have you explained the text or have you changed it?
If you change the 'clear proof,' then you are making God out to be a deceiver who gave a 'clear proof' that was actually a lie for 600 years.
If the Quran was sent to explain what was 'revealed for them,' it was sent to explain the Bible we have today. Since the Quran contradicts the Bible, it didn't explain the revelation—it tried to overwrite it. By its own definition in 16:44, the Quran fails."
This verse essentially puts the Bible in the position of the Original Document and the Quran in the position of the Commentary. If the commentary contradicts the original document, the commentary is discarded.
Since 16:44 frames the Quran as an explanation, while Surah 29:46 commands Muslims to argue with Christians only in the "best way" because of our shared belief in the same God and Book!