The Self-Donation of God, chapter 11:
"Because of the taxis of Christ’s threefold office discussed in the last chapter, we will begin our discussion of the threefold office with the regal (munus regium). Jesus is the true Davidic king (Matt 1:1, 9:27, 15:22, 20:30, 20:31, 21:9, 21:15; Luke 1:32, 1:69; Rom 1:3; Rev 3:7, 5:5, 22:16.) who fulfills Gods' promises to David (2 Sam 7; Ps 2, 89, 110). As the true Davidic king, he is the restorer of humanity's place within the original creation, as well as the fulfiller of the Abrahamic testament and its promise of universal blessing.
The fact that Jesus is a descendent of David, and therefore the true inheritor of the promise of the Davidic testament, is clear from the genealogies provided for us by Matthew and Luke. The question of whether Jesus was a literal descendant 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 the God of the New Testament to be a faithful fulfiller of his promises. This would place the promise of the gospel itself into question. Therefore, the issue of Christ’s literal descent from David cannot be papered over with the typical Liberal Protestant shrug and appeal to the post-Enlightenment fact/value split.
Due to the extreme skepticism characteristic of many of the practitioners of the historical-critical method, the genealogies of the New Testament have been under fire since the eighteenth century. Nevertheless, contrary to popular scholarly belief, the Gospel genealogies contain much to recommend themselves on purely historically grounds. This would be true even if they were not guaranteed to us by the fact of their inclusion in the utterly truthful Word of God."