The Christian Era

When the sixth century abbot, Dionysius Exiguus, was calculating the date to begin the calendar based on the Christian Era, he determined that December 25, in the 753rd year since the founding of the city of Rome, was Christ’s date of birth. Because January 1 was celebrated as New Year’s Day in sixth century Rome, the abbot chose January 1, 754 A.U.C. (from the founding of Rome) as a suitable date to begin the Christian Era. Thus 754 A.U.C. became 1 AD, the year of our Lord.


Dionysius erred in his calculation of the year in which Christ was born. According to Matthew's Gospel, Jesus wasn’t born after the reign of Herod the Great but rather during the reign of that same Herod.


After Herod ascertained when and where the Messiah was born, he ordered the slaughter of all male babies in Bethlehem and its suburbs causing the flight of Mary, Joseph, and the baby Jesus to Egypt. Upon Herod’s death, the holy trio returned to Palestine.


An eclipse of the moon occurred on March 13, 750 A.U.C. shortly before the death of Herod the Great. That was documented by Josephus in his Antiquities (17.6.4). Thus Christ was most likely born in 749 A.U.C., the year before Herod's death.

Nevertheless, 754 A.U.C. was designated 1 AD. The abbot’s system of numbering years did not allow for a year zero. When 1 BC ended, 1 AD began. Indeed, December 31, 1 BC was followed by January 1, 1 AD. Therefore, if we synchronize Christ’s actual birth to the abbot’s system of numbering years, He was born in 5 BC.