Christmas and "Pagan Customs"

I just finished talking with our daughter on the telephone. She told me about a conversation she'd had with a guy at work that nearly made me bust a gut.
This fellow told her knowingly, "You know, most of the customs of Christmas go back to the pagans. Even the date for Christmas goes back to them."
He said this with a triumphant knowing tone, as if to say, "This all proves Christmas is bunk."
But any informed Christian can tell you that we have no idea when Jesus was actually born. No Christan claims that December 25 is the actual birthday of Jesus. It's just the day we've chosen to celebrate the birth.
For centuries, residents of the northern hemisphere have celebrated varied holidays involving light, just around the Winter Solstice. In the first century Roman world in which Christianity was born, the festival of Saturnalia, celebrated in honor of a god of agriculture, took place during the Solstice. Evergreens were hung. Gifts were exchanged. Candles were lit.
Christians, a marginalized minority, appropriated the customs of the "pagans" in order to celebrate the birth of Jesus, the One they believed was "the light of the world." This is Who the evangelist John wrote about in the prologue of his Gospel:
...The true light, which enlightens everyone, was coming into the world. He was in the world, and the world came into being through him; yet the world did not know him. He came to what was his own, and his own people did not accept him. But to all who received him, who believed in his name, he gave power to become children of God, who were born, not of blood or of the will of the flesh or of the will of man, but of God... [John 1:9-13]
The Christian reclamation of old customs may have been a somewhat subversive act for a persecuted band of believers to employ to worship and honor the God they'd come to know through Jesus Christ. But people who think that it all disproves the revelation of God in Christ are guilty of poor logic...or wishful thinking.