Not surprising at all, it reminds me of the Latter-day Saints.
Muhammad was raised in the Christian home and had a revelation that Christian faith was incorrect. His revelation gave birth to the Quran to back up Islam doctrine.
Joseph Smith when through a similar stage in life that produce the Book of Mormon to back up Latter Day Saints doctrine.
Both founders started out in Christian Faith then deviated to start new religions.
HARD to call ISLAM a religion. They are very destructive
Thee is a mounting body of historical evidence that Mohammad and his story are either a fiction or happened at some other later date.