The next Non Issue in Luke’s birth narrative is Joseph’s return to his ancestral home, Bethlehem, to register for the census. (I deal with the first Non Issue -- the scope of the Augustun decree --, here). Many commentators are completely dismissive, conjuring up images of an empire-wide census requiring everyone to return to the city of their ancient ancestors. E.P. Sanders, for example, claims that "the entirety of the Roman Empire would be uprooted by such a decree" and asks, "Why should Joseph have had to register in the town of one of his ancestors forty-two generations later?" The Historical Figure of Jesus, pages 86-87.
Paying closer attention to the Gospel of Luke itself, however, reveals that the author is careful not to describe the census itself as requiring registration in one's ancestral home. Rather, Luke only references any ancestor when noting that Joseph registered in Bethlehem because he was of the House of David. When referring to the census itself Luke notes that in response to the decree people were returning to each one's "own city."
Now in those days a decree went out from Caesar Augustus, that a census be taken of all the inhabited earth. This was the first census taken while Quirinius was governor of Syria. And everyone was on his way to register for the census, each to his own city. Joseph also went up from Galilee, from the city of Nazareth, to Judea, to the city of David which is called Bethlehem, because he was of the house and family of David, in order to register along with Mary, who was engaged to him, and was with child.
Luke does not say that everyone has to return to the home of their distant ancestors. Rather, he says that each person was registering in “his own city” and that Joseph registered in Bethlehem, “because he was of the house and family of David.”
A close reading of Luke reveals that the premise upon which Sanders bases his reconstruction is without foundation in the text. Nowhere does Luke say that the census of Quirinius required people to travel to the home of their ancestors. On the contrary, the text reads, "the decree went out . . . that the whole world should be registered.” It does not say how or where. . . . There is nothing in the narrative of Luke which departs from common practices. Rather, he simply describes the perfectly normal response of the people to the decree: "All went to their own towns to be registered."
Mark D. Smith, "Of Jesus and Quirinius," Catholic Biblical Quarterly 62 (2000), page 289.
If Joseph was not required to travel to Bethlehem by the mere fact of his blood line, why did he? What was it about being of the House of David that would have made Bethlehem his "home city" in some way, assuming Luke considers that description to apply? Luke does not specify the connection. For his story, the important point he wanted to emphasize is that Joseph was a descendant of King David. A plausible, perhaps likely, answer seems to be that because of his family's association with Bethlehem, Joseph owned property in or near Bethlehem.
One of the deans of Lukan studies, I. Howard Marshall, reaches this conclusion.
Although Luke does not make it clear, it must be presumed that Joseph had some property in Bethlehem. It is unlikely that everybody would have been compelled to return to their ancestral homes, but in view of Joseph’s Davidic descent, which is more important for his story, Luke has stressed this aspect of the matter.
I. Howard Marshall, Commentary on Luke, NIGTC, page 101-03.
Dr. Richard Carrier of the Secular Web and Infidels.org reaches a similar conclusion: that Luke means to suggest that Joseph had some property in or near Bethlehem.
[I]t is very doubtful that Luke would use a system of census taking that his every reader would know didn't exist--certainly, his apologetic aims would fail if his "explanation" held no water. Therefore, there must have been something to it--for even if fiction, it had to play on some fact or else the lie would be obvious to everyone. At the very least, we can suppose many Jews believed they could trace a lineage to some ancestor in the town of their family land, so as to justify their belonging there and to secure their claim in perpetuity, not to mention the mere glory of tracing one's line to some tribal hero (many Greeks and Romans did just the same). We can suppose that Luke believed (or wanted his readers to believe) that Joseph had family land in Bethlehem, and that this was because it was a portion of David's land, and since Jewish Law required the return of sold land every fifty years (Lev. 25:10-28), it was impossible to ever be dispossessed of it--thus, it might have seemed obvious to every Jew that any family plot could be traced to an ancient owner, even if this really wasn't the case. And as noted in the text above, residing outside the taxed area would not exempt any landowner from taxation or the related census so long as he held any property or citizenship in the taxed region.
Those who assume that Luke describes a census that requires everyone to travel to the home town of their distant ancestors is paying insufficient attention to the text. Luke deliberately moves from the general to the specific. He describes a census requiring people to be registered. He then notes that in general people were returning to their "own city" to register. He then notes that Joseph traveled to Bethlehem to register. It seems the general rule is that people be registered in their own town and that is what they did. For Joseph, because he was of the House of David, he chose to register in Bethlehem. Whether this is because he had grown up there, had an interest in property in or near there, or wanted to maintain his status in good standing as a descendant of King David, Luke does not specify. This is hardly surprising as the connection itself is of no consequence. What is important to Luke and his readers is that Jesus was born in Bethlehem and that his legal father, Joseph, was a descendant of King David.