Seven centuries ago a Christmas carol, often sung today, was written in Latin, with a Latin title that meant "With Sweet Shouting." The great composer, Johann Sabastian Bach, liked it so much he arranged it for the organ, and John Mason Neale later standardized the hymn in English.

In English the title was changed to "Good Christian Men Rejoice." The first stanza tells us what every Christian understands about the season called Christmas.

Good Christian men, rejoice,
With heart and soul and voice;
Give ye heed to what we say:
Jesus Christ is born today.

Ox and ass before Him bow,
He is in the manger now;
Christ is born today,
Christ is born today!

Now even the world understands that Christians celebrate Christmas as the birthday of Jesus Christ. But the reason why Christians rejoice at…