A.D.
Anno Mundi, (A.M.), or “Year after Creation”, is a calendar era based on the biblical accounts of the creation of the world and subsequent history. It also means "Year of the World" in Latin. It is a measure of time with reference to the creation of the Earth as recorded in Genesis.
B.C. (Before Christ) and B.C.E. (Before Common Era) mean the same thing, previous to year 1 A.D. (Anno Domini) and 1 C.E. (Common Era) meaning the same as well. The notations are used in many schools and academic settings to avoid reference to Christianity.
The year zero does not exist in the Anno Domini (A.D.) system commonly used to number years in the Gregorian calendar and in its predecessor, the Julian calendar. In this system, the year 1 B.C. is followed by A.D. 1.
The Hebrew calendar is a lunisolar calendar, meaning that months are based on lunar months, but years are based on solar years.
Pope Benedict XVI, the head of the Catholic Church (2005 – resignation in 2013) asserted that the Christian calendar is based on a miscalculation because Jesus was born sometime between 7 B.C. and 2 B.C., the Telegraph reported.
Jesus was born earlier than previously believed, meaning the Christian calendar based on the year of his birth is off by several years, the Pope argues in his book.
"The calculation of the beginning of our calendar - based on the birth of Jesus - was made by Dionysius Exiguus, who made a mistake in his calculations by several years," Pope Benedict XVI writes. "The actual date of Jesus' birth was several years before."
Indeed, the Christian calendar was created by highly reputed as a theologian, accomplished mathematician and astronomer Exiguus (Latin: "Dionysius the Humble", (English: "Denis The Little"), a 6th-century Monk born in Scythia Minor (probably modern Dobruja, in Romania and Bulgaria. Historian Cassiodorus calls him a Monk, but tradition refers to him as an Abbot. Credited to him are a collection of 401 ecclesiastical canons, and the now commonly used Anno Domini (A.D.) era, which counts years based on the birth of Jesus.
Ironically “A.D.” does not mean “after death”, as many people suppose. It stands confusingly for a Latin phrase: Anno Domini “in the year of the Lord” (the year Jesus was born).
He came up with this concept in the year 525, or, 525 year after the birth of Jesus at the request of Pope St. John I. The chronology still current, was a modified Alexandrian computation (95-year tables evolved by the Patriarch Theophilus of Alexandria) based on Victorius of Aquitaine’s 532-year cycle. Whereby, he wrongly dated the birth of Jesus according to the Roman system (i.e., 754 years after the founding of Rome) as Dec. 25, 753.
This claim isn't a new one, and did not have any consequences, but it was the first time the leader of the Church stated it publicly such doubts about one of the keystones of Catholic tradition.
The Bible does not specify when Jesus was born, and it seems Dionysius based his calculations on vague references to Jesus' age.
This is one of several new arguments the Pope, 85, made in his book. He also said that, despite what most people think of as a typical nativity scene, there were no animals present at Jesus' birth.
The book is the final installment of Benedict's trilogy. The first book dealt with Jesus' public ministry, and the second with His death. Both previous books topped bestseller lists in Italy. All three books are published under the Pope's real name, Joseph Ratzinger, (short for Joseph Aloisius Ratzinger), who was born in Marktl am Inn, Bavaria, Germany...
Food for thought!