Surah 13:36 is a significant verse in the "Ar-Ra'd" (The Thunder) chapter that highlights the reaction of the People of the Book to the Quranic revelation, providing a behavioral anchor for the argument regarding the preservation of previous scriptures.
Surah 13:36:
Those unto whom We gave the Scripture rejoice in that which is revealed unto thee, and of the clans there are who deny some of it. Say: I am commanded only that I worship Allah and ascribe unto Him no partner. Unto Him I pray, and unto Him is my return.
For those analyzing the relationship between the Quran and the Bible, this verse provides a "psychological proof" that challenges the idea that the 7th-century Bible was corrupted.
The verse states that the People of the Book (Jews and Christians) rejoice (yafraḥūna) in what was being revealed to Muhammad.
One only rejoices in a new message if they recognize it as being in harmony with the truth they already possess.
If the Quran "confirms" the Bible, and the People of the Book rejoice because they see their truth in it, then the Bible they held in the 7th century must have been the unadulterated Word of God. If that 7th-century Bible is true, then the Quran—which contradicts that Bible on the Crucifixion, the Atonement, and the Deity of Christ—cannot be true.
You cannot "rejoice" in the confirmation of a book that you no longer have or that has been changed into a lie. The joy mentioned in 13:36 stems from the continuity the Jews and Christians supposedly felt.
If a 7th-century Christian rejoiced because the Quran spoke of Jesus, but then found that the Quran denied Jesus’s status as the Son of God and His death for sins, the rejoicing would turn to rejection. By claiming they do rejoice, the Quran asserts that its message is a mirror of their Scripture. If the mirror (the Quran) and the object (the Bible) do not match, the "Confirmation" claim fails.
The verse mentions that some "clans" (groups) deny some of it (ba'ḍahu).
The rebuke is not that they have a corrupted book, but that they are selective in accepting the new revelation that supposedly matches their book.
This reinforces the idea that the standard of truth remains the Scripture they were given (Al-Kitab). If the Quran's validity is measured by how well the People of the Book "rejoice" in its alignment with their Scripture, then the Bible remains the Primary Criterion.
Surah 13:36 says the People of the Book 'rejoice' in the Quran. They would only rejoice if they recognized their own Scripture within it.
This proves their Scripture was present and recognizable in the 7th century. Since we have those same manuscripts today, and they explicitly contradict the Quran's core theology, the Quran's claim of 'rejoicing through recognition' is a historical and logical impossibility.
Either they didn't rejoice because the Quran is different, or they did rejoice because their book is true—and if their book is true, Islam is false.