Justify Christmas and not Jewish and Muslim holy days.
Can't be done. How many Americans attend a Christian church twice a month? How many tithe? How many give a rip about the date of the birth of Christ?
In polls, how many say Christian because they think they should, without any tangible demonstration of that?
Christianity, along with the European Caucasian, is being phased out of relevance in the US, and there really is no excuse for Christmas without celebrating many, many more religious feasts.
Thanksgiving is a good one, though. Except for the Native Americans.