Why Christmas is on 25 December

The Gospels describe Jesus’s birth, but no date. For the first few centuries, Christians mostly celebrated Easter; birthdays weren’t a major focus.

The first record

The earliest evidence for 25 December is the Chronograph of 354, a Roman calendar that reflects church practice around 336. By the end of the 4th century the date had spread through much of the Christian world.

Two explanations

1. The solstice and the sun. In the Roman calendar, 25 December was the winter solstice, and from 274 the emperor Aurelian promoted a festival of Sol Invictus, the “Unconquered Sun”, on that day. On this view, the church placed Christ’s birth on a date already associated with light returning. Saturnalia, a December festival of feasting and gifts, adds to the picture.

2. The calculation. Some early Christians believed Jesus was conceived on the same date he would die, which they placed on 25 March, the Roman date of the spring equinox. Add nine months and you get 25 December. This explanation doesn’t need a pagan festival at all.

Historians still debate which mattered more. Both may have played a part.

Christmas on 7 January

Many Eastern Orthodox churches, such as those of Russia, Serbia and Georgia, still follow the older Julian calendar for church dates. Their 25 December currently falls on the Gregorian 7 January. They celebrate the same day, counted on a different calendar.