The terms BC and AD are used when referencing years in the Gregorian calendar, the calendar system used in most parts of the world today. BC stands for “Before Christ” and AD stands for “Anno Domini”, a Latin phrase meaning “in the year of our Lord”.
Years before 1 AD are labeled BC (or B.C.), meaning “before Christ”. For example, 800 BC indicates 800 years before the birth of Jesus Christ. The year 1 BC was immediately followed by AD 1. There was no year zero in between the two designations. Years following 1 AD are labeled AD, meaning “in the year of our Lord”. For example, the year 2022 AD is 2022 years after the birth of Jesus.
The BC/AD dating system was originally devised in the 6th century by a monk named Dionysius Exiguus. He wanted to replace the dating system used at the time, which was based on the reigns of Roman emperors. Since Christianity was becoming the dominant religion in Europe, it made sense to begin reckoning years from the birth of Jesus Christ. Dionysius tried to determine when Jesus was born and assigned that year as 1 AD. All years before that were designated BC.
It’s important to note that Dionysius did not get the year of Jesus’ birth exactly right. Based on other historical evidence, most scholars agree Jesus was likely born between 6-4 BC. However, the BC/AD system of Dionysius stuck and is still used around the world today.
History and Origin
The system of numbering years BC and AD was invented in the 6th century by a monk named Dionysius Exiguus. He devised this system to replace the Diocletian Era dating system, which was based on the reign of Roman Emperor Diocletian. Since Christianity was spreading throughout Europe, Dionysius thought it would be better to reckon years from the birth of Jesus Christ rather than a Roman emperor.
To come up with a year for the birth of Jesus (which he assigned as 1 AD), Dionysius tried to determine the year of Jesus’ conception and then added nine months to get the year of his birth. He chose the conception year based on Easter tables that gave possible dates for the Passover celebration. His calculations did not match perfectly with the actual year of Jesus’ birth, which most modern scholars believe was between 6-4 BC.
Despite this discrepancy, Dionysius Exiguus’ BC/AD dating system gained widespread usage in Europe within a few hundred years. The English monk Bede was an early adopter and promoter of the BC/AD system, using it in his influential ecclesiastical history in the early 8th century. By the 9th century it was the standard dating system throughout most of Europe.
The BC/AD system spread to other parts of the world as Europeans explored and colonized many lands. It became the most widely used dating system, usually replacing various regional eras based on rulers or events. Even though the BC/AD calendar counts years differently than the birth year of Jesus, it retains the original purpose – labeling years in relation to the approximate time of Christ’s birth.
Meaning Behind BC and AD Labels
The BC/AD labels stand for “Before Christ” and “Anno Domini” respectively. AD is a short form of the Latin phrase “Anno Domini Nostri Iesu Christi” which translates to “In the Year of Our Lord Jesus Christ.” This phrase refers to the year of Christ’s birth.
The BC abbreviation stands for “Before Christ.” It designates the years preceding 1 AD, when Dionysius believed Christ was born. There is no zero year between BC and AD. The year 1 BC is immediately followed by AD 1.
Originally, AD was placed before the year (e.g., AD 2022). Now it is more common for AD to be placed after the year (e.g. 2022 AD). Occasionally both forms are still used (2022 AD or AD 2022). BC always comes after the year (e.g. 800 BC).
Although BC is a shorthand for “Before Christ,” and AD for “Anno Domini,” the labels refer specifically to whether the year is before or after year 1 AD according to the Gregorian calendar. The BC/AD system was not actually designed to mark years in reference to Jesus’ birth year per se, but simply to divide history into two epochs – the time before and after year 1 AD.
Approximate Years for Jesus Christ’s Birth and Death
As mentioned earlier, Dionysius Exiguus did not determine the exact year of Jesus Christ’s birth when he created the BC/AD system in the 6th century. Through other historical sources and methods, modern scholars have been able to estimate approximate dates:
- Jesus was likely born between 6-4 BC
- Jesus began his public ministry around AD 27-29
- Jesus was crucified and died around AD 30-33
The main evidence scholars use to estimate Jesus’ birth year includes the writings of the Jewish historian Josephus, who mentioned an astronomical event that occurred between 6-5 BC. Other evidence comes from the Gospel of Luke itself, which gives historical details linking Jesus’ birth to the time of King Herod the Great’s reign which ended in 4 BC.
Most scholars believe Jesus’ ministry on earth lasted 2-3 years until his death and resurrection. Based on data from the Gospels and other ancient writers, his crucifixion is estimated to have occurred between AD 30-33.
The mismatch between Dionysius’ calculations and the actual birth year of Jesus does not invalidate the BC/AD system. Even though the 1 AD year is a few years off, it still divides history into a “Before Christ” epoch and “After Christ” epoch as Dionysius intended.
Alternative Dating Systems
There are a few alternative dating systems used mainly by academics and scholars, although the BC/AD system remains the most widely used in both secular and religious contexts.
In academic works, it is common to see the abbreviations BCE (Before Common Era) and CE (Common Era) used in place of BC and AD. For example, 800 BCE instead of 800 BC, and 2022 CE instead of 2022 AD. This substitutes religious titles with secular phrases based on the Common Era.
There have been other attempts to restart the calendar from different events, such as the French Republican Calendar starting from 1792 during the French Revolution and a Chinese socialist calendar starting from 1949. However, none of these gained much traction.
A few atheist or anti-Christian groups have advocated replacing the BC/AD system with a “Human Era” system that would restart the calendar from 10,000 BC, but this has had negligible adoption. Some groups have also proposed using the approximate year of the first homo sapiens as year 1, but there is too much uncertainty around dating that event.
Since the Gregorian calendar and BC/AD system has been deeply intertwined with human history for over a millennium, it remains the defacto international standard. Alternative systems exist mainly for academic and secular purposes.
Astronomical-Time Keeping Methods
Astronomers, physicists, and other scientists do not normally use BC or AD notation in scholarly work. Instead, they keep time using advanced astronomical chronometers that are accurate to a small fraction of a second per thousands of years. Some examples are:
- Atomic clocks – Accurate modern atomic clocks now keep civil time using oscillations of atoms like cesium at extremely high frequencies. This allows timekeeping accuracy to billionths of a second.
- Orbital parameters – The motion of the earth around the sun and orientation with respect to stars allows astronomers to define timescales that are accurate over tens to hundreds of thousands of years. Precession, obliquity, and eccentricity cycles relate the earth’s orbit to calendar time.
- Radiometic dating – Radioactive isotopes in rocks or organic matter decay at known rates governed by physics, allowing an age-date to be extrapolated going back millions or billions of years into the past. Examples are radiocarbon dating and uranium-lead dating.
- Astrochronology – Layers containing sedimentary rocks and fossils can be correlated across continents using astrochronology techniques. Geological records of climate cycles synchronized with earth’s orbital parameters or solar output variations allow precise dating of events hundreds of millions of years ago.
However, these advanced methods require high-tech equipment and expertise not accessible to most people. For common everyday purposes worldwide, the Gregorian calendar with BC/AD notation remains the standard. The BC/AD system has endured as the most simple and globally recognized way to communicate chronological information.
Implications of the BC/AD Calendar on Christianity
The BC/AD dating scheme has cemented the idea of Jesus Christ’s life as the central event of human history and the dividing line between epochs. Counting years as “Before Christ” or “In the year of the Lord” is a universal recognition of Christ’s significance in shaping world history.
Every time a date using “BC” or “AD” is written down by anyone – from government officials to scientists to ordinary people writing checks – it is bearing witness to the coming of Christ into the world. Jesus is the reference point for marking the progression of human civilization.
Writing or speaking dates in terms of BC and AD also serves as a subtle reminder of biblical history. The more this notation is used throughout cultures worldwide, the more Jesus Christ remains at the center of our understanding of the past and its direction toward the present. Each date is like a mini-testimony pointing toward the reality of Christ.
Due to its widespread use for over 1000 years, the BC/AD system has become deeply embedded in global thought. Attempts to replace it with other dating systems have failed. This signifies how firmly Jesus Christ and the events described in the Bible have become anchored into history and human development.
Key Scripture Verses Relating to BC and AD
The Bible itself does not use BC or AD notation, since this was devised many centuries later. However, here are some key verses from Scripture that relate to the period marked by BC/AD in Gregorian calendar terms:
“But when the fullness of time had come, God sent forth his Son, born of woman, born under the law.” (Galatians 4:4)
“Of the increase of his government and of peace there will be no end, on the throne of David and over his kingdom, to establish it and to uphold it with justice and with righteousness from this time forth and forevermore. The zeal of the Lord of hosts will do this.” (Isaiah 9:7)
“Therefore the Lord himself will give you a sign. Behold, the virgin shall conceive and bear a son, and shall call his name Immanuel.” (Isaiah 7:14)
“In him was life, and the life was the light of men. The light shines in the darkness, and the darkness has not overcome it.” (John 1:4-5)
These verses point to God’s plan of redemption through Jesus and the epochal interface between “darkness” and “light” marked by Christ’s coming as a turning point in history.
Frequently Asked Questions
Why does the calendar jump from 1 BC to AD 1?
There is no zero year between BC and AD. The year 1 BC was immediately followed by AD 1. This reflects the mathematical conventions of Dionysius Exeguus’ time. The number zero and its role in mathematics was still developing in Europe at that point.
What do scholars use instead of BC and AD?
In academic literature, it is common to see BCE (Before Common Era) used instead of BC and CE (Common Era) instead of AD. This provides religiously neutral notation but has the same dates/years.
When did BC/AD usage become widespread?
Usage of BC/AD became common across Europe by the 9th century, especially after promotion by the English monk Bede. It was later spread to other regions, replacing many local dating systems, as Europeans explored and colonized the globe.
How accurate was Dionysius in determining Jesus’ birth year?
Dionysius set 1 AD as the year of Jesus’ birth. However, based on other historical evidence, it is likely Jesus was born between 6-4 BC. Dionysius miscalculated the year, but his system still divides history into epochs before and after Christ.
Do atheists or non-Christians use BC and AD?
Yes, the BC/AD system is used worldwide by both Christians and non-Christians. Attempts to replace it have failed. BC/AD has become the standard way to communicate dates across cultures and religions.
What scripture prophecies relate to Jesus’ coming as a transition point?
Isaiah 9:7 prophesies of Jesus ruling forevermore. Isaiah 7:14 foretells his virgin birth. Galatians 4:4 mentions Jesus coming at the fullness of time. These all point to Jesus as a turning point.
Conclusion
In summary, the BC/AD dating scheme devised by Dionysius Exiguus in the 6th century has become the standard system worldwide for numbering years in the Gregorian calendar. BC stands for “Before Christ” – designating years prior to 1 AD. AD stands for the Latin “Anno Domini” meaning “in the year of our Lord” – designating years after 1 AD. This splits history into two epochs separated by the approximate time of Christ’s birth.
Although Dionysius miscalculated the exact year of Jesus’ birth, the BC/AD system still effectively divides history into the period “Before Christ” and the period after Christ designated as “In the year of the Lord.” This dating method bears witness to Jesus Christ as the fulcrum of history and reinforce his significance in shaping human civilization.