“Hear, O Israel: The Lord our God, the Lord is one."
Then another aspect is revealed - Jesus as Lord is part of Monotheistic worship:
yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.
1 Cor 8:6
But then we get to Islam. They also include a man that had walked the earth but unlike to Paul this man is believed to be nothing but a human prophet:
I testify that there is one god Allah and Muhammad is his final prophet.
I believe the fact to become a Muslim you must include a mere man as a statement of faith - a man whom you are to emulate, a man who accompanies God's name throughout the Quran (the whole "Allah and his Apostle") really raises some questions on how important Muhammad himself believed he was.