Isaiah proclaims that YHWH is most alive and present in the promise of the Davidic kingship. As we heard last week in 2 Samuel 7, a Davidic king will rule over YHWH's people forever. And so Isaiah reiterates that promise to proclaim that once again "the Davidic child has been born for us and has been given to us."
I cannot help but feel that this promise of joy in a new king is deeply problematic. We have had kings before, and they have been troubling at best and monstrous at worst. They have robbed and cheated and lied and murdered their way to the throne of power (see David and Solomon, above all), and the very last things many of them have concerned themselves with are "justice and righteousness," those two characteristics that are the hallmarks of those who revere YHWH and who serve the people of YHWH. The history of the Davidic kingship is far more promise than reality.
Is it any wonder that the early Christians seized upon this joyful promise of Isaiah and found in it the promise of their Messiah, the babe of Bethlehem, who grew up to teach and heal and love and, unlike the Davidic kings of Israel, to represent the living image of a God of justice and righteousness?
Yet, what is to prevent we modern Christians from falling back into the darkness and gloom of those ancient Israelites, who could not see the great light of their promised just and righteous kings? We, like them, are beset with the same blinders, the same masks that shield us from the light of justice and righteousness. And just because we proclaim Jesus as the heir of David's promise is no guarantee at all that we will really have seen the great light, promised so long ago. As always, the proof is in the pudding. As Joshua said in the 24th chapter of the book that bears his name, "You (we) are witnesses against yourselves (ourselves)" whether or not we in fact will be followers of YHWH. So, if the great light has truly come for us, how can the world see in us the reality of that light of justice and righteousness?