Christmas and Western Civilization

The holiday season has many traditions, some ancient, some modern. Among the most recent is a paradoxical one: complaints, yearly renewed, about the public recognition of Christmas as a religious celebration. As these observances get underway (see here and here), we might do well to ask the following question: what, if anything, has Christmas contributed to Western Civilization that could earn the respect even of the secularist and hence win his acquiescence in its ongoing public acknowledgment?