My point was that Mohammed did not accept either the Old or the New Testaments, but took the parts that he thought useful to his cult, mixed with a heavy dose of moon-worshipping paganism. That’s what syncretism is all about.
The Muslims claim to be an “Abrahamic people” but this is just because Mohammed seized the name Abraham to justify himself and make it easier to subdue Jews and Christians when he began his first attacks on this defenseless population. Islam was a conquest strategy by a megalomanic nobody, sort of like Hitler, who couldn’t have achieved anything on his own but had this bizarre ability to play the public, particularly by taking advantage of old grievances - and ignorance. And both of them, Hitler and Mohammed, were ruthless and incredibly cruel.
I’m not sure that Mohammed took any “parts” of either Testament; after all, there is only one verse out of the entire Bible quoted in the Koran. Everything else is a complete rewriting of whatever appears in the Bible.