History of Christmas: The Year — How Could Jesus be born 4 B.C.?

Bill Petro
3 min readNov 29, 2022
Dionysius Exiguus

It’s obvious that Jesus was born on December 25, A.D. 1 (Anno Domine, “the year of our Lord”), right? Not so fast.

OK, was it in Year Zero?

No, there wasn’t a Year 0; the calendar went from 1 B.C. to A.D. 1.

We know that Herod the Great (who killed all the babies in Bethlehem younger than two years of age) died in the Spring of 4 B.C., according to the Jewish historian Josephus *.

The king was quite alive during the Wise Men‘s visit in the Nativity story told in the Gospel of Matthew. So Jesus would have to have been born before this time, anywhere from 7 B.C to 4 B.C. (Before Christ, or before himself!)

Christmas Calendar Gap

Why is there a gap of this much time in our modern calendar?

We owe this to a Roman monk-mathematician-astronomer named Dionysius Exiguus, or Dennis the Little, but known to his close friends as Dennis the Humble. During the 6th century A.D., he unwittingly committed what has become history’s most significant numerical error related to the calendar.

Originally from Scythia Minor, north of the Danube River delta in modern Romania near the Black Sea, he relocated to Rome. He was best known for translating many ecclesiastical canons from Greek into Latin, including the famous decrees from the Councils of Nicaea and Chalcedon.

He tried to reform the Western calendar to center around Jesus’ birth; he erroneously placed the date of the Nativity in the year 753 “from the founding of Rome” (753 A.U.C. or Ab Urbe Condita), even though Herod died only 749 years after the founding of the city of Rome, as everyone knows; it was in all the papers. The cumulative effect of Dionysis’s calendar error, the same calendar we use today, was to give Rome’s founding the correct traditional date. Ultimately, however, the calendar is at least 4 to 7 years off for the birth of Christ.

Did you celebrate the Y2K change of Millennium in 1997?

* Some recent research suggests that the dating of Herod’s death might be up for debate and could be dated 1 B.C. The argument is either the counting of his reign was off, or there was a typesetting error in all editions of Josephus since 1544. I tried to get to the bottom of this by researching an earlier edition of Josephus at the British Library in London but could only get my hands on a French translation from 1492. Regrettably, I couldn’t read medieval French.

Bill Petro, your friendly neighborhood historian

Subscribe to have future articles delivered to your email. If you enjoyed this article, please consider leaving a comment.



Bill Petro

Writer, historian, technologist. Former Silicon Valley tech exec. Author of fascinating articles on history, tech, pop culture, & travel. https://billpetro.com