The fact that Jesus is a descendent of David and therefore the true inheritor of the promise of the Davidic covenant is clear from the genealogies provided for us by Matthew and Luke. The question of whether Jesus was a descendent of David is in fact not a trivial one, but rather concerns God's faithfulness to his promises. If the Messiah was not David's son, then we cannot understand him to have been the faithful God whom we encounter in the revelation of the gospel. Therefore, this question cannot be papered over with the typical Liberal Protestant shrug and predictable appeal to the Kantian fact/value split.
Due to the nearly paranoid skepticism displayed by many of the practitioners of the historical-critical method, the genealogies of the New Testament have been under fire since the time of the Enlightenment. Nevertheless, contrary to popular scholarly belief the Gospel genealogies contain much to recommend them historically, even if they were not guaranteed to us before hand by their inclusion in the inerrant Word of God.
The first aspect that recommends them historically is the probability that Jesus would be a Davidic descendent. David after all, had many descendents, not least as a result of his own and his Son’s prodigious harems. For this reason, a rather large number of people in ancient Israel could very credibly claim descend from him. That this knowledge of this descent would also be accessible is equally plausible. It has also been noted by many, that Second Temple Jews maintained their own genealogical records in both oral (mostly peasants) or in written forms (elites). Josephus also reports that prior to the destruction of Jerusalem in 70 A. D., that the Jews maintained a large deposit of public genealogical records. If the Synoptic Gospels were written prior to 70 (as the ending of Acts suggests and, as well as the lack of references to the destruction of the Temple) then it is not unreasonable to think that the Evangelists might have had access to these records.
We may also go further. As Gerd Theissen has rightly noted, Jesus’ family were extremely prominent in the early Church and therefore can be considered the source of the New Testament's source of the assertion that Jesus was of Davidic descent. Paul calls Jesus the “son of David” (Rom 1:3) and he clearly knew Jesus relatives as both Galatians and Acts demonstrates. If that is the case, then Jesus’ family must have claimed descent from David. Going beyond Theissen, we might suggest that if Jesus' relatives did claim descent from David, they must have maintained some sort of genealogical records and these records could very well have been disseminated them within the early Church. Such dissemination would have been a useful tool against those who contested Jesus' claims to be the true Davidic Messiah.
Historical skeptics must also recognize, urges Theissen, that it is highly unlikely that Davidic descent would be something that Jesus' family or the early Church would generate after the fact. There were a variety of messianic expectation in first century Judaism and not all of them made it necessary for the Messiah to be of Davidic descent. Conversely, there were major disadvantages to claiming descent from David insofar as it might make one the object of intrigue by Roman officials fearful of messianic upstarts. As an example of this, Eusebius shares with us that Jesus’ nephews (apparently still leaders in the early Church at the end of the first century) were harassed by Domitian when he discovered that they held their uncle to be the true Davidic king and the ruler of the universe. For this reason, Pannenberg is incorrect to assert that Jesus could never have conceived of himself as the Davidic king. The historical evidence presented to us in the New Testament clearly shows his family (and therefore he) were quite self-conscious of being the heirs of the Davidic monarchy.
An issue that is perhaps more troubling in approaching the question of Jesus' descent is that in significant respects Matthew and Luke's genealogies do not give the appearance of agreeing with one another. This problem is by no means insoluble and has been addressed in a number of ways. The beginning of a solution might come by recognizing (as was observed in chapter two) that Matthew’s genealogy has obvious and rather wide gaps in it. The intention of these gaps (as we suggested) was to highlight Jesus' role as bringer of the universal Sabbath and Jubilee by dividing Jesus' genealogy into forty-two generations (Mt. 1:17). Nevertheless, in observing this, we must note that although Matthew's theological goal was somewhat symbolic, it was not fictive. Hence, appealing to Matthew's theological goal in structuring his genealogy in a particular way does not absolve us of the problem that to the extent he intends to literally list Jesus' ancestors he stands in an apparent conflict with Luke.
As a result of recognizing this problem, a number of solutions have been offered. Probably the most common solution is that each represents a separate parent of Jesus’ genealogy. Perhaps Matthew gives us the descent from Joseph and Luke from Mary. This division is suggested by the fact that the two Evangelists focus on the aforementioned parent in their recounting of the infancy narrative. All things considered, this probably the best solution to the problem.
There are nonetheless a number of objections against this view as well. The first and most common is that both genealogies appear to trace Jesus' descent through Joseph. On the surface, neither deal with the descent of Mary. This may be solved by the fact that, as J. Stafford Wright has noted, in ancient Judaism childless or sonless marriages often times resulted in legal transference of sonship. There are also a number of examples of this occurring in the Old Testament (1 Ch 2:34, Ezr 2:61). Hence, it could be plausibly suggested that Mary's family might very well have lacked sons and that Joseph was named her father's legal heir. A lack of sons in a family is a common enough phenomenon in any culture and historical period that this is by no means a stretch.
Some might also object that this solution suggests that both parents were descendents of David. At first glance might be considered unlikely. Nevertheless it in fact actually fits well with historical data that we possess concerning Second Temple Judaism in particular and ancient Mediterranean culture in general. Historical research has shown that most Jewish marriages tended to be among close relatives during the Second Temple period. Scholars have also noted that much of the pseudepigraphal literature of this period (notably the book of Jubilees) strongly encourages marriage with close kin. The presence of this cultural practice in this literature suggests that endogamy was considered to be the ideal. If Mary and Joseph were therefore anything like their contemporaries, it is highly likely that they were closely related and therefore both descendents of David.