Discrepancy in Calendar Years: When Was Christ Born?

Dear Catholic Exchange:

I read in a couple of sources that the birth of Jesus occurred between 6 and 3 B.C. I always thought the changing of time as marked by B.C. and A.D. had to do with the birth of Jesus. Could you please explain why Jesus was thought to be born B.C.? Also, how did the calendar come to have the “zero” year if Jesus was three to six years old when they began marking the time by His birth?


Dawn Quinn

Dear Dawn,

Peace in Christ!

Traditionally, Jesus was said to have been born in 1 A.D. However, scholars now believe that the reckoning used to number the years on our calendar according to the birth of Christ was off by three to six years.

Christian calendars (including the Gregorian calendar we now use) have Christ’s birth as the “start-date.” With the Julian calendar, used at the time of Christ’s birth, years were figured according to the reign of the emperor. Years were not simply added as they are now, so figuring the length of time from the fifth year of the reign of Constantine to the eight year of the reign of Diocletian involved more than basic mathematics. The practice of counting years according to Christ’s birth did not start until the 5th or 6th century. Dionysius Exiguus, a Scythian monk and linguist used historical documents and simple math to discern when the annunciation took place and first year of Jesus Christ’s earthly life began. This method of dating did not become commonplace until the 10th or 11th century.

Scholars have since discovered the Dionysius was likely off in his reckoning. However, by the time that was discovered, it was too late to change the dating to account for the error. Therefore, we retain our dating system and recognize that the birth of Christ likely occurred between 6 and 3 B.C. rather than in 1 A.D.

I hope this answers your question. If you have further questions on this or would like more information about Catholics United for the Faith, please contact us at 1-800-MY-FAITH (693-2484). Please keep us in your prayers as we endeavor to “support, defend, and advance the efforts of the teaching Church.”

United in the Faith,

Amy Barragree

Information Specialist

Catholics United for the Faith

827 North Fourth Street

Steubenville, OH 43952

800-MY-FAITH (800-693-2484)

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