As a side note, this is probably one of the reasons I'm sort of a Bible nerd; there is just so much there. I think I know the Bible pretty well and yet it is just such a vast and varied collection of literature that you could spend your whole life studying it without exhausting all that God has to offer through it. This is also just one of the reasons that I preach from the lectionary. By following a series of prescribed readings of four passages of Scripture for each Sunday over a three year cycle, I am lead to passages that I would not otherwise preach. This helps our congregation's life together to be shaped by the whole of Scripture, not just my own favorite texts.
Well anyway, on to the actual passage. I'm not sure yet how all of this will coalesce into a sermon but for now this is what I am noticing about 2 Samuel 23:1-7.
My Bible titles this section "David's last song". As such, it appears to be a summary of what David hoped that his reign as king was or what he hopes that the reign of future kings will be. It's almost like David's farewell speech or a final will and testament: his last chance as king to influence the course of Israel's history with a few final words. Perhaps, in this way it is similar to the book of Deuteronomy which is a sort of farewell speech from Moses as the Israelites are poised to enter the promised land but Moses knows he will not accompany this new generation in that joyous journey. So he does all that he can to set them on the right path since he can no longer lead them; he reminds them of what God has done and how they should continue to be faithful to God as a result.
Similarly, David holds up a vision of what Israel's king should be even after he is gone. He gives this vision of the king's role authority by saying that the Spirit of the Lord has spoken through him. At the center of this kingly ideal is righteousness; that is, the king must be one who rules justly and fairly out of reverence for God. David says the king who does this will bring life to his kingdom in the same way that sunlight brings life to the grass after the rain.
Then David says in v. 5 "Truly is not my house so with God?". This seems to be an odd question since David and the writer(s) of 1 and 2 Samuel know that David's house has not been this way with God. There were times when David had abused his power as king rather than reigning righteously and David was still reaping the consequences of that action through the misconduct of his children. David himself did not live up to the ideal portrait of kingly rule which he paints in this song.
But the very next line of the song puts a different spin on things. "For He (God) has made an everlasting covenant with me (David), ordered in all things and secured; for all my salvation and all my desire, will He not indeed make it grow?" David's house being right with God doesn't seem to depend so much on what David has done as it does on what God has done. David's house is not "so with God" because David was perfect but because God has chosen David and his descendants. It is God's sovereign choice and not a mere accident of human history which has made David and his descendants to be the kings of Israel. Because of that, David holds out hope that despite his own household's imperfections, his descendants will still be "as the light of morning" to the kingdom of Israel. On the other hand, "the worthless" (a term used earlier in 2 Samuel to describe Sheba, a man who rebelled against David's reign as king) are thorns that have to be handled carefully but will be thrown out and burned up.
In short, this song is a reaffirmation of the kingly ideology that is prevalent throughout the story of David. It expresses the deeply held belief that David was not just a king but a righteous ruler put in place by a righteous God who would be faithful to Israel by keeping a descendant of King David on the throne forever and seeing to it that any who rebelled ("the worthless") against God's anointed king would be defeated.
Undoubtedly, the lectionary editors have chosen this passage for this final Sunday before Advent because it is Christ the King Sunday. Just as this passage expresses the ancient Israelite hope of what Israel's king would be, so it expresses our hope as followers of Jesus that he is God's true anointed, that he speaks for God, and that one day he will indeed reign in righteousness and that all the worthless powers that have threatened his reign as king will ultimately be defeated.