From the Qu'ran 19:16-36:
Mention in the book of Mary, when she withdrew from her people to a place facing east,
and she took a veil apart from them; so We sent to her Our spirit who presented himself to her as a man without faults.
She said, "I take refuge in the All-merciful from you! If you fear God..."
He said, "I am a messenger from your Lord, to give you a boy, pure."
She said, "How shall I have a boy when no mortal has touched me, nor have I been unchaste?"
He said, "It shall be so! Your Lord has said: "It is easy for Me; We have appointed him as a sign to the people and a mercy from Us; it is a thing decreed."
So she conceived him, and withdrew with him to a far-away place.
And the pains of birth drove her to the trunk of the palm-tree. She said, "I wish I had died before this happened, and had become a thing forgotten!"
But he who was below her called to her, "No, do not sorrow; see, your Lord has set below you a stream.
Shake the palm-trunk towards you, and fresh, ripe fruit will tumble down on you.
So eat thereof and drink, and be comforted; and if you see any human being, say, "I have vowed a fast to the All-merciful, and today I will not speak to any human being."
Then she brought him to her folk, carrying him. They said, "Mary, you have surely committed an improper thing!
Sister of Aaron, your father was not an impure man, nor was your mother an unchaste woman."
Then she pointed to him but they said, "How can we speak to one who is still in the cradle, a child?"
He said, "Lo, I am God's servant; God has given me the book, and has made me a prophet.
He has made me blessed, wherever I may be; He has enjoined me to pray, and to give the alms, so long as I live,
and likewise to cherish my mother; He has not made me a tyrant, unprosperous.
Peace be upon me, the day I was born, and the day I die, and the day I am raised up alive!"
This is Jesus, son of Mary, a statement of the truth about which they are in doubt.
It is not for God to take a son unto Him. Glory be to Him! When He decrees a thing, He only says to it "Be," and it is.
Surely God is my Lord, and your Lord, so serve Him. This is a straight path.
(Trans. from Calder, Mojaddedi, and Rippin, Classical Islam: A Sourcebook of Religious Literature)
You were not expecting this one. Don't pretend.
Jesus is in fact regarded as a prophet in Islam -- the "last prophet," or at least the last in that tradition. This isn't the only time Jesus comes up in the Qu'ran or in Islamic thought in general, but as this comes somewhere being a "nativity story" it seemed the one to check out.
Parts of the story look vaguely familiar. Earlier in the 19th sura (chapter, roughly) we get an account of Zacharias, the father of John the Baptizer, that also looks a little bit like Luke's narrative. Here the visitation of Mary by a "messenger from your Lord" isn't necessarily that dramatically different from Luke's story, including Mary's insistence on her innocence. From there it does take a different turn, one slightly resembling Old Testament accounts of the exile of Hagar, before the truly unusual part, in which one of three things has happened; (1) the infant Jesus starts to preach; (2) the infant Jesus grows up into a man really quickly; or (3) the time frame of the narrative jumps ahead many years without warning us.
Still, the key here is something that the passage takes great pains to deny, something that helpfully reminds us what the really important part of the Christian nativity narrative is.
"This is Jesus, son of Mary," looks innocent enough. But as the sura continues, it becomes clear that "son of Mary" is a bit of a proxy for something else, i.e. "not a son of God." This becomes clear with the statement "It is not for God to take a son unto him."
And this, friends, is the Big Deal.
When we manage not to get distracted by the Christmas pageants and cantatas and such (much less the tinsel and Santa Clauses and radio carols playing Christmas music the day after Halloween), this is the nugget that undoes everything. Our faith insists, if sheepishly at times, that this whole messy narrative is nothing less than God undoing history by breaking into it in the form of a human, from infant all the way up the chain. "Incarnation," to use the fancy theology word. "Emmanuel" as the prophets put it -- "God with us," God as one of us not in a cheesy pop-song way but God as human as God as human as God, both/and, 100% and 100%.
This is scandalous. Gods don't besmirch their divinity getting mixed up in human form (leaving aside those crazy Greek/Roman deities). This isn't just Islam talking; many early Christians struggled mightily with just how exactly this whole incarnation worked without God somehow being diminished in the process. Some of the earliest creeds in the Christian tradition came into existence due to struggles over this very claim of God Incarnate.
Christmas is, despite the way many churches approach it, not the most important feast day in the Christian year -- you have to look to the Maundy Thursday/Good Friday/Easter sequence for that. But Christmas is not without its depth and significance. The in-breaking of God into humanity, all undignified and messy and in a no-account Judean backwater, is a claim that the world cannot bear.
To borrow a phrase from Linus and "A Charlie Brown Christmas" again, that's what Christmas is all about.