A few years ago my wife and I were in Aleppo, Syria, at Christmas time. While most people think of Syria as a Muslim country—and it is—it also has a significant Christian population. In fact, some early Christian sects in Syria are still active, and others have found refuge there from genocide and persecution taking place in neighboring areas.
The year we were there, the weeks before Christmas coincided with Ramadan. These dual holy days gave a quiet, single-minded spiritual focus to daily life for both Muslims and Christians. They didn't join in each others' observances. But as we visited with both, it was clear that the lives of both Muslims and Christians had a sincere focus on the spiritual occasion at hand.
In Syria, Christmas was an important, but quiet, honoring of Jesus' birth.