Atheist Revolution and on a number of other atheist blogs I read is that the holiday is now thoroughly secular. Most people, it is claimed, no longer regard Christmas as a religious holiday at all. When one considers how thoroughly commercialized Christmas has become in the U.S., it is easy to see why people would suggest that it is now a secular holiday. However, a recent Gallup poll calls this claim into question.
According to Gallup, 51% of Americans surveyed consider Christmas a "strongly religious" holiday, over 60% attend religious services, and 78% say that they take time to reflect on the alleged birth of a historical Jesus. In fact, the results suggest a slight increase in the proportion of those celebrating Christmas who feel that it is a "strongly religious" holiday since the previous poll was administered.
To be fair, Gallup's results also indicate that Americans who celebrate Christmas are more likely to participate in various secular traditions than religious ones. Still, the Gallup data do not appear to support the commonly heard claim that Christmas is not a religious holiday for most Americans.
H/T to Jobsanger