Church History · AD 525

Dionysius Exiguus Invents the AD Calendar

In AD 525, a monk in Rome named Dionysius Exiguus started counting years from the birth of Jesus, which he called Anno Domini, the year of the Lord. He was probably off by a few years, which is why Jesus is dated about 6 to 4 BC. Bede made the system popular in the 700s and helped introduce counting backward before Christ.

Read it in the Bible: Galatians 4:4 Matthew 2:1 Luke 2:1-2 Psalm 90:12

In AD 525, a monk living in Rome named Dionysius Exiguus began numbering years from the birth of Jesus Christ. He called it Anno Domini, Latin for in the year of the Lord. That is where AD comes from. He was probably off by a few years, which is why we now say Jesus was born about 6 to 4 BC, before Herod died in 4 BC. A few centuries later, the English monk Bede made the system popular and helped start the habit of counting years before Christ. Today most of the world uses Dionysius' numbers, whether people write AD or CE.

Who Was Dionysius Exiguus?

Dionysius was a monk born around 470 in Scythia Minor, near the Black Sea, in what is now Romania and Bulgaria. He moved to Rome around 500 and spent the rest of his life there translating Greek church documents into Latin and collecting church law. He died around 544.

His nickname, Exiguus, means small or humble. Most scholars think he chose it himself out of humility. It's a little ironic that the humble little monk ended up changing the way the whole planet counts time.

Why Did Dionysius Start Counting From Jesus?

He was not trying to reform the calendar. He was trying to figure out Easter. The date of Easter changes every year, based on the moon and the spring equinox, and churches had argued for centuries about how to calculate it. In 525, Pope John I asked Dionysius to prepare a table of future Easter dates.

The older Easter tables he worked from counted years from the start of the reign of Emperor Diocletian in 284. Dionysius didn't like that. Diocletian was the emperor who had launched the Great Persecution against Christians. Dionysius wrote that he did not want to keep alive the memory of a tyrant who persecuted Christians, so he numbered his years from the incarnation of Jesus instead. His table began with the year 532.

That is a great story. A persecutor tried to wipe out the church, and in the end the church stopped counting by his name and started counting by Jesus' name.

Was Dionysius Wrong About When Jesus Was Born?

Almost certainly, by a few years. Dionysius never explained how he picked the year. But the Gospels say Jesus was born while Herod the Great was king.

After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east arrived in Jerusalem, Matthew 2:1

Most historians date Herod's death to 4 BC, based on the Jewish historian Josephus and an eclipse he mentions. Since Herod was still alive when Jesus was born, and he ordered the killing of the boys two years old and under, Jesus was probably born about 6 to 4 BC. Some scholars argue for a slightly later date for Herod's death, around 1 BC, which would move Jesus' birth closer to Dionysius' count. But the traditional and majority view is 4 BC.

So yes, it is a little funny to say Jesus was born about five years before Christ. Blame the math, not the Bible. The Birth of Jesus page on this site explains the clues in more detail.

Who Added BC to the Calendar?

Dionysius only counted forward. For a few centuries his system was used mainly for Easter tables. The person who made it famous was Bede, an English monk and scholar. In 731 he finished his Ecclesiastical History of the English People, and he dated events by years of the Lord throughout.

Bede also needed a way to date things that happened before Jesus, like Julius Caesar's invasion of Britain. So he used a Latin phrase meaning before the time of the Lord's incarnation. That's the idea behind BC, which means before Christ. Bede's work was widely copied, and through scholars like Alcuin at Charlemagne's court, AD dating spread across Europe in the 800s. Counting years backward before Christ became common much later, in the 1600s and 1700s.

Is There a Year Zero?

No. The calendar goes straight from 1 BC to AD 1. Zero wasn't used as a number in Europe in Dionysius' day. That's why the 21st century technically began on January 1, 2001, not 2000. Try telling that to everyone who partied in 1999.

What Do BCE and CE Mean?

BCE means before the Common Era, and CE means Common Era. They use the exact same numbers as BC and AD. Only the labels change.

The idea is older than many people think. The astronomer Johannes Kepler used the phrase vulgar era, meaning common era, in 1615, and Common Era shows up in English by 1708. Jewish scholars used it in the 1800s, since they didn't want to call Jesus Lord. In the late 1900s it became common in schools, museums and scholarly books, partly to be neutral toward people of other faiths.

Some Christians prefer BC and AD because the labels point to Jesus. Others use BCE and CE in academic settings without any problem. Either way, the numbers still count from Jesus. Every time someone writes the date, they are, in a sense, pointing back to Bethlehem.

Why the AD Calendar Matters for You Today

History itself is divided by the life of Jesus. No other person has had that effect. Paul said God sent His Son at exactly the right moment.

But when the time had fully come, God sent His Son, born of a woman, born under the law, Galatians 4:4

Each new year is another year of the Lord. That makes it worth asking how we will spend the one we're in.

So teach us to number our days, that we may present a heart of wisdom. Psalm 90:12

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Questions People Ask

Who invented AD dating?

A monk named Dionysius Exiguus invented the Anno Domini system in Rome in AD 525 while preparing a table of Easter dates. He chose to count years from the incarnation of Jesus instead of from the reign of the persecuting emperor Diocletian. The English monk Bede made the system popular in 731.

What does AD stand for?

AD stands for Anno Domini, Latin for in the year of the Lord. It does not mean after death. Years before Jesus are marked BC, meaning before Christ.

Why was Jesus born in BC?

Dionysius Exiguus probably miscounted by a few years. The Gospels say Jesus was born while Herod the Great was alive, and Herod died in 4 BC. So Jesus was likely born about 6 to 4 BC.

What is the difference between BC/AD and BCE/CE?

They use exactly the same year numbers. BCE means before the Common Era and CE means Common Era, while BC means before Christ and AD means in the year of the Lord. BCE and CE are often used in academic settings to be religiously neutral.

Is there a year zero?

No. In the AD system, 1 BC is followed directly by AD 1. That is why centuries technically begin with years ending in 01, like 2001.

Sources

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