As a post-Vatican II Catholic myself, I share the ecumenical beliefs of most modern Christians. One of these is that Islam, being one of the three "Abrahamic" religions, has a great deal in common with Christianity, and that these common roots should be cultivated. It contains truth, and wisdom, and has built civilisations.Islam shares nothing in common with Christianity.
That Mohammed transmitted (or fabricated) perversions of Biblical characters and events does not make Islam a continuation, completion, or correction of Christianity.
Neither can Islam be called an "Abrahamic" faith. When combating the heresy and apostasy of His own day, Christ told an unbelieving audience that if they were truly children of Abraham, they would do what Abraham did. Abraham never did what Mohammed preached and practiced. The prophet from Hell made the most vile and barbaric violations of the Ten Commandments "divine."
The words and actions of Mohammed prove clearly that Allah is no Christ. For example, Jesus said, "Love your enemies," but according to Mohammed, Allah commands, "kill the unbelievers wherever you find them . . . ." Jesus said that He is the Son of God, but Mohammed taught that whoever says Allah has a son blasphemes. Third, Jesus warned that whoever causes a little child to sin would be better off if a large stone were tied around his neck and he were thrown into the depths of the sea, but Mohammed said of his raping little nine-year-old Aisha, "If this is from Allah, then it must happen."
Mohammed may have received revelations from a "deity" (even the grotesquely self-serving ones), but there is no way that his god was the Biblical One.