In the early church many people thought that celebrating birthdays was a pagan practice, so they didn’t like the idea of celebrating a birthday for Jesus.

Later, however, Christians decided it was more effective to create alternatives to pagan celebrations than to eliminate or ignore them. Sometime during the fourth century they decided to celebrate Christmas on December 25 — already a day of Roman celebration.

When days became short in the winter, the Romans were afraid that the earth was dying. So they celebrated the Feast of the Unconquerable Sun on December 25 in honor of the sun’s return and longer days. While Romans were busy celebrating the return of their sun, a band of renegades calling themselves Christians celebrated the arrival of God’s Son.

— Doug Peterson, “Many Are Called,” (Grand Rapids, MI: Zondervan Publishing House, 1992).