I was inculcated to research a spot of history for this time of year by someone’s offhand comment about its primarily christian roots; he suggested it was incorrect to consider christmas a pagan holiday.
Attis in Phrygia, whose birthday of December 25th was shared by Persian sun-god Mithras (who was, it must be noted, also popular with the Romans);
Zorastians celebrated Yalda, on the solstice;
The Mesopotamians celebrated Marduk in his annual successes over the forces of chaos;
In short, just about everybody celebrated winter to some extent or another.
As far as the modern holiday goes, we can pretty much give credit to early popularization by the Queen (who through Prince Albert introduced the Christmas tree and a probably apocryphal piercing) and, in 1834, the publication of A Christmas Carol.
Alabama was the first state to declare Christmas a legal holiday in 1836, and in the 1860’s the indomnitable retailer Macy’s began popularising the notion that one should break one’s bank open over your loved one’s heads by remaining open until the witching hour upon Christmas eve.
In the following years doing large displays that culminated in a massive parade that eventually got ‘christened’ after that other secular holiday, Thanksgiving.
The original gentleman was, frankly, correct: it is disengenuous to call Christmas as we celebrate it today a pagan holiday; of course, it is equally so to consider it a Christian holiday.
Indeed, Christmas is most entirely a secular holiday, of no faith whatsoever.