This fact establishes a contradiction that cannot be reconciled in theology or belief.
While it may be true that a pious and moral Muslim can live in harmony next to a pious and moral Christian and that they can maintain a secular peace (which is a very ood thing) ... particularly when the Muslim does not belong to a sect that literally believes and practices jihad and the Christian actually practices a true earthly walk in the footsteps of Christ ... it is not true that their theology or belief system with respect to Christ Jesus is close. In fact, as I have stated, from that perspective it is unreconcilable.
This is certainly true of orthodox (not just Orthodox) Christianity. But an old, and formerly very powerful Chrisian heresey -- Arianism, agrees with Islam on this. Started by the Byzantine Bishop Arius, it was very popular in the Eastern Roman Empire during the 4th century, then was successfully fought by mainline Christians, led by the Pope of Rome, among others.
The great Church Council at Nicea, presided over by the Emperor Constantine had as a main purpose the making of a decision on the divinity of Christ. It produced the Nicene Creed, which virtually all Christians accept today ('True God and True Man'). The heresy was destroyed in the Empire. Unfortunately many of the German tribes, including the East and West Goths, and the Franks were converted by Arian missionaries in the meantime. When they took control of the provinces of the Western Empire, they actively persecuted Christians who accepted the Creed.
Eventually they all converted to mainline Christianity, but much damage had been done to the fabric of society, and Spain was so weakened, since Arianism was not eliminated until the 6th century, that its defeat by the Moors was made much easier.
In a sense, then, Islam could be considered to be a heresy of Christian Arianism.