The Quran Verse
Surah 4:82
Then do they not reflect upon the Qur'an? If it had been from other than Allah, they would have found within it much contradiction.
By setting the standard that a divine book cannot contain contradictions, the Quran effectively condemns itself.
Because it contains historical contradictions (denying the crucifixion), mathematical contradictions (the inheritance error of 27/24), and theological contradictions (angels teaching magic in Surah 2, or changing the rules of salvation and marriage), the text fails its own test for divine origin.