The Quran Verse
Surah 14:10
Their messengers said, 'Can there be doubt about Allah, Creator of the heavens and the earth? He invites you that He may forgive you of your sins...'
In this Surah, various prophets from different eras and cultures (Noah, ‘Ad, Thamud) all use the exact same vocabulary, arguments, and rhetorical style as Muhammad.
In the Bible, prophets have distinct voices, historical contexts, and specific social messages. In the Quran, every prophet is essentially a "clone" of Muhammad, facing the exact same Meccan-style opposition.
This suggests a single human author projecting his own contemporary struggles onto historical figures, rather than recording actual distinct historical events.