It seems to me that Christmas is more a cross cultural service than any other. Our priest gave an ok sermon about the Christmas Truce during WWI. The trench warfare was beyond inhumanity. HIding time deep in the trenches, the armies could hear their favorite Carols sung by their enemies. All these armies were Christian with religious leaders endorsing the slaughter. One drunk soldier stood up on a trench and sang a Christmas hymn. Rather than being mowed down with gunfire, all up down the line, all the enemy soldiers started serenading the others with Christmas songs in the spirit of Christmas. Before long, they were visiting the enemy trenches. They sang rounds with each country singiing a part. Enemy solides started to visit their enemy treanches, bringing precious champagne to toast them and showing photographs of their families. Sports games ensued.
The leaders of the war were appalled and decided to punish anyone with Christmas cheer toward the enemy. There was talk that they could retake the situation and peace would be renegotiated. Death threats were administered. The celebrations ended. Soon all these friends ( almost all with invitations to visit the enemy after the work) were slauhtering each other again. We sang Silent Night in alternative verses of English, German, and French.
Until a recent film that was well done, this incident was largely buried.
I don't need to know Modern European History or any other field to enjoy Christmas songs. Art masterpieces, such as Da Vinci, Michaelangelo, Raphael, bring me to tears without knowing any composition details. It affects my whole being. I feel these painters/scultptors reveal more of the holy than a million religoius thesis. The same is true of music. I don't need to know the libretto or the history. My whole body is overcome by wonder.