OK...it seems to me that Islam has more in common with Judaism than either have with Christianity. The gist of the Koran ( Quran ) is more similar to the Talmud, and visa versa, than to anything in the Gospels or the letters of the Apostles.
This might lead someone to believe that Christianity wasn't so much an off-shoot to Judaism, or a reform, than a rejection to traditional Jewish dogma.
Was Jesus a reformer...or was he just dealing with the religious ideology of the day and, as a consequence, using an association to make his points but having no such real association with them?
The general principles of Christianity are more in line with Buddhism than with Judaism. And Judaism is far more in line with the principles of Islam.
So it would seem that Islam is the natural off-shoot of Judaism...and Christianity was the birth of a new religion, based upon the principles laid down.