Andy Webb has a very helpful post on this topic.
Darryl Hart asks when Presbyterians became Adventists? With the help of Leigh Eric Schmidt makes some very interesting and important points about the way commercial interests coincided with the interests of revivalist evangelicalism.
Then, of course, there is the problem of the sheer sentimentalism of the holiday. It’s worth considering.
UPDATE 18 Dec 09
David Strain makes a good point about the evangelistic opportunities provided by Christmas.