[N.B.: This series of posts, of which the following is the second in the series, is a republication for newer readers of the series I did on this topic in 2009. I have updated the posts as necessary with more contemporary references.]
In my first post in this series on the date of Christ's Nativity, the purpose was to fix an absolute date -- a terminus ad quem -- by which Jesus had to have been born. We saw that such a boundary was established by the date of Herod's death, and that with reasonable certainty (and going against the scholarly consensus of the last 120 years) the latter date had to have occurred in late January - early February of 1 B.C. Since Herod used the information the Wise Men gave him to determine that the "King of the Jews" they came to worship had been born within the previous two years, that points to sometime in the years 3-2 B.C. as the date of Christ's birth.
In the last post in this series, I will marshal the astronomical evidence for an exact date, by reconstructing the "signs" in the Babylonian night sky which caused the Wise Men to set out on their journey. First, however, in this post I want to summarize the evidence we have from other sources as to the date of the Nativity. And for this purpose, there is no better resource than the revised edition of Jack Finegan's Handbook of Biblical Chronology. (He in turn draws upon the earlier scholarship of Ernest L. Martin and others who have examined the earliest Christian sources.)
We can begin with the Gospel of Luke, chapter 2, verses 1-7:
2:1 Now in those days a decree went out from Caesar Augustus to register all the empire for taxes. 2:2 This was the first registration, taken when Quirinius was governor of Syria. 2:3 Everyone went to his own town to be registered. 2:4 So Joseph also went up from the town of Nazareth in Galilee to Judea, to the city of David called Bethlehem, because he was of the house and family line of David. 2:5 He went to be registered with Mary, who was promised in marriage to him, and who was expecting a child. 2:6 While they were there, the time came for her to deliver her child. 2:7 And she gave birth to her firstborn son and wrapped him in strips of cloth and laid him in a manger, because there was no place for them in the inn.
Luke tells us unequivocally that Jesus was born during the reign of Caesar Augustus, at a time when he had published a decree for all of those subject to Roman rule to go to their "own town" to be registered. (The Greek word Luke uses, "apographo", can have the meaning "register/enroll for taxes", but that was not its only use. It was also used in registering for other purposes, such as for a census [which was frequently, in the Roman empire, used as a tax base].) In Judea, where Bethlehem was the "home town" of Joseph, this happened when Quirinius was governing in Syria.
There has been much dispute about the accuracy of Luke's account, because Quirinius did not actually become the Roman governor of Syria until 6 A.D., which would be far too late as a birth date for Jesus. However, there are records which indicate that Quirinius may have served as a legate or commander in Syria before that (and note that Luke is specific that "this was the first registration taken when Quirinius governed in Syria"). The second registration is probably the one which Luke alludes to in Acts 5:37, in speaking of the rebel Judas the Galilean. And the clue to what was probably Luke's "first registration" is supplied from the records of the Emperor Augustus himself. He records, in his Res gestae divi Augusti inscribed on the walls of a temple in Ankara,
In my thirteenth consulship the senate, the equestrian order and the whole people of Rome gave me the title of Father of my Country [Pater Patriae].
As we shall see below, we can identify the thirteenth year of Augustus' consulship with the period July 1, 3 B.C. to June 30, 2 B.C. For the "whole people of Rome" to have bestowed the title, there would have had to have been first an enrollment or registration, for each to record his consent before a Roman official. (The Jewish historian Josephus records (Ant. 17.41-45) that " . . . the whole Jewish nation took an oath to be faithful to Caesar," except for six thousand Pharisees, who refused to swear.) The Christian historian Orosius gives the fullest account of the event:
Augustus ordered that a registration be taken of each province everywhere, and that all men be enrolled . . . This is the earliest and most famous public acknowledgment which marked Caesar as the first of all men and the Romans as lords of the world, a published list of all men registered individually. This first and greatest enrollment was taken, since in this one name of Caesar all the peoples of the great nations took oath, and at the same time, through the participation in the census, were made a part of one society.
Accordingly, it is Luke himself who gives us our first clue to the year in which Christ was born: if the "first registration" to which he refers is the first great registration of the whole Roman world ordered by Augustus, then Christ was born sometime between July 3 B.C. and June 2 B.C. As we shall see below, all of the early Christian writers concurred in this point. However, in order to appreciate what those writers say, we first have to understand a little about how regnal years were calculated in the time of Augustus.
We know that Augustus died in August, 14 A.D., but when exactly did he begin his rule? For the custom of early Christian writers was to date an event by telling us in what year of an emperor's reign it happened. (Thus Luke writes, at the beginning of his third chapter: "In the fifteenth year of the reign of Tiberius Caesar, when Pontius Pilate was governor of Judea, and Herod was tetrarch of Galilee, and his brother Philip was tetrarch of the region of Iturea and Trachonitis, and Lysanias was tetrarch of Abilene, during the high priesthood of Annas and Caiaphas, the word of God came to John the son of Zechariah in the wilderness. . . .")
Now as we all know well, Augustus was called Octavian when his uncle Julius Caesar was assassinated on the Ides of March in 44 B.C. He had picked his nephew as his successor, and so under this theory, Octavian's first regnal year began upon the official unsealing and reading of Julius Caesar's will, which occurred on March 17, 44 B.C. And given his known date of death, on August 19, A.D. 14, we have our first match with ancient sources: the Jewish historian Josephus records that the reign of Augustus Caesar lasted for "fifty-seven years, [five] months and two days (War 2.168; Ant. 18.32).
At the time he wrote, Josephus lived in Rome, and this is how Romans would have reckoned their calendar. But for others who lived in Palestine, Egypt, or northern Africa (such as Tertullian), recall that there was in the years immediately after Julius Caesar's death a triumvirate, ending in a war, during which Mark Antony (and not Octavian) ruled over Egypt. Antony was decisively defeated by Octavian at the Battle of Actium on September 2, 31 B.C., and he died, along with his consort Cleopatra, in the latter part of August, 30 B.C. The exact date of Antony's death is uncertain, but it was just before the first day of the new year in the Egyptian calendar, Thoth 1, which corresponded to August 29, 30 B.C. So for Egyptians, the reign of Augustus over their country did not begin until that point, and the regnal years were numbered forward from August of 30 B.C., instead of from March of 44 B.C. Thus for writers counting years from an Egyptian standpoint, Augustus ruled for only forty-three years, not fifty-seven. One has to keep in mind, therefore, that when a writer says "In the twenty-fourth year of the reign of the Emperor Augustus", one must first determine which regnal calendar the writer is using.
Now, add some further chronological wrinkles, consisting of the knowledge that certain writers counted regnal years as beginning with the first day of the Roman year (January 1), and that fractional years before that date could either be counted as a regnal year or not, according to the writer's way of thinking, and you are ready to embark on an interpretation of early Christian sources as to the year of Christ's birth.
Our earliest source is Irenaeus, who wrote (Against Heresies 3.21.3, circa A.D. 180): "Our Lord was born about the forty-first year of the reign of Augustus." Using the Roman regnal system, this would be sometime between March of 3 B.C. and March of 2 B.C.
Next we have Clement of Alexandria, writing in his Stromata (1.21.145, circa A.D. 194): "And our Lord was born in the twenty-eighth year . . . in the reign of Augustus." Alexandria is in Egypt, and so using Egyptian regnal reckoning, this would have been between August 29, 3 B.C. and August 28, 2 B.C. -- again, in good agreement with Irenaeus. But Clement goes on to make this remarkable statement: "From the birth of Christ . . . to the death of Commodus are, in all, 194 years, one month, thirteen days." The Emperor Commodus was murdered on December 31, A.D. 192. Thus Clement asserts that Jesus was born precisely on November 18, 3 B.C.
Tertullian, who lived and wrote in Roman Africa (ca. A.D. 160-220), assembles his data as follows:
After Cleopatra, Augustus reigned forty-three years.All the years of the empire of Augustus were fifty-six years.In the forty-first year of the empire of Augustus, when he ha[d] been reigning for twenty-eight years after the death of Cleopatra, the Christ [was] born.And the same Augustus survived, after Christ [was] born, fifteen years.
From these statements, we can see that Tertullian is counting only whole regnal years, and is using both the Roman and the Egyptian system. Augustus may have died almost exactly forty-four years from the day Cleopatra died, but he did not live for a full final Egyptian year, and so Tertullian counts his reign as just forty-three years from August 29, B.C. 30. Likewise, leaving out the fractional year after Julius Caesar died, and not counting the fractional last year of Augustus' life, Augustus reigned for fifty-six full years. Having established his method of reckoning, Tertullian thus is asserting that Christ was born in the same time period as stated by Clement, that is, between August 29, 3 B.C. and August 28, 2 B.C. That gave Augustus another fifteen full years of rule until his death in A.D. 14. (Remember, there is no zero year between 1 B.C. and 1 A.D., so you have to subtract 1 when performing the math: -2 (B.C.) to 14 (A.D.) is 16 - 1 = 15 years.)
Julius Africanus, the "father of Christian chronography", lived from circa A.D. 170 to A.D. 240. He is best known for his Chronography, in which he calculates that there were 5,500 years between the creation of the world with Adam and the birth of Christ. By co-ordinating his calculations of other dates, which he relates to the dating of the Greek Olympiads, Jack Finegan shows (Handbook [rev. ed. 1998], sec. 291) that this agrees with all the other earlier Christian writers just cited, and equates to 3/2 B.C. His contemporary, Hippolytus of Rome (ca. A.D. 170 - 236), uses a slightly different means of reaching the date of creation, but gives exactly the same year (3/2 B.C.) for the date of Christ's birth.
In a Greek fragment of his Homilies, Origen (ca. A.D. 185 - ca. A.D. 253) gives the same dates and calculations for Christ's birth as does Tertullian.
Eusebius of Caesarea, the great historian of the early Church, gives (ca. A.D. 325) the "forty-second year of the reign of Augustus" for Christ's birth, but from his other datings of Augustus' reign we can see that he counted the first (fractional) year in 44 B.C. as a full year, so that he, too, agrees with all the preceding writers, and places Christ's birth in 3/2 B.C. Epiphanius (A.D. 315-403) uses the same reckoning as does Eusebius, and gives the additional datum that in Augustus's "forty-second year", when he says Christ was born, the consuls were Octavian (for the thirteenth time) and Silvanus. Table 41 in Finegan's Handbook (pp. 88-89) relates the Roman consulships to Augustus' regnal years, and shows that the year so indicated by Epiphanius ran from July 1, 3 B.C. to June 30, 2 B.C. (And note how this correlates with the year in which Augustus ordered his "first great registration" of all the Roman world, as discussed above.)
We thus have a remarkable unity among all the known Christian writers in the first four centuries as to the year when Christ was born. It was only when the sixth-century monk Dionysius Exiguus, who had been given the task of continuing Cyril of Alexandria's table of Easter dates (which used a calendar reckoned from the rule of the Emperor Diocletian [A.D. 284-305]), decided to do his calculations running not from a pagan's reign, but from the Nativity itself, that our current calendar was permanently established. Dionysius used a calendar based on counting the years since the founding of Rome (ab Urbe condita, or A.U.C.), and he selected A.U.C. 753 as the year of the incarnation. However, since ancient writers did not all agree on the relationship between the Olympiad years and A.U.C. dates, the system which Dionysius selected made the equivalent of A.U.C. 753 equal to B.C. 1 in Dionysius' calculations.
Given that by the time Dionysius was writing (A.D. 525), Christians had begun to celebrate December 25 as the Feast of the Nativity, Dionysius thus regarded Christ as having been born on December 25, B.C.1, and began his system of anno Domini reckoning with the succeeding January 1. There was no awareness in Roman numbering at the time of the function of zero on a number line. Thus Dionysius' calendar passed directly from December 31, B.C. 1 to January 1, A.D. 1, and we have been stuck with the counting difficulties so created ever since.
It becomes all the more exasperating, then, when a copyist's error in a sixteenth-century manuscript of Josephus has saddled us with the mistake of dating Herod's death to 4 B.C., resulting in an even greater discrepancy between the birth of Jesus and A.D. 1. By going back to the remarkable consensus of the early Christian writers, and by correcting for Herod's death according to the clue which Josephus provides of a lunar eclipse occurring shortly before his death, we can begin to make some sense out of the actual chronology of Jesus' life.
The next step will be to add in the astronomical clues, which are truly remarkable -- indeed, spectacular.