I would look to Paragraph 841 of the CCC:
841 The Church’s relationship with the Muslims. "The plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Muslims; these profess to hold the faith of Abraham, and together with us they adore the one, merciful God, mankind’s judge on the last day."330
330 LG 16; cf. NA 3.
The Journey Home: Daniel Ali - former Muslim
I think the connection between Muslims & Christians is through Abraham although their understanding of God is different - as it is with Judaism. Arab Muslims believe they are descendants of Ishmael, & Ishmael was circumcised along with Abraham & all of the men of the household in Genesis 17:
Now as for Ishmael, I will heed you: I hereby bless him. I will make him fertile and will multiply him exceedingly. He will become the father of twelve chieftains, and I will make of him a great nation.
But my covenant I will maintain with Isaac, whom Sarah shall bear to you by this time next year.
You can read more about the descendants of Ishmael in Genesis 25: http://www.usccb.org/bible/genesis/25