This upcoming Sunday, we will (hopefully) hear Psalm 17 between the First and Second Readings. Verse 5 reads "My steps have kept to your paths; my feet have not faltered", and verse 15 begins with "I am just". Now, if this were merely Christological in the sense that we could see this being prayed by Jesus (who is righteous and just), we'd be done. But it's a psalm of David. David prayed this. David, the king of Israel who got Bathsheba pregnant, had her husband killed, etc. That David. Psalm 51 attests to his sinfulness: how can he be saying he's just here?
Of course, with the forgiveness and mercy and grace of God, he can be just (and not simply say he's just), but I think this psalm takes on a different meaning when we think of its fulfillment in Jesus Christ. It's still a psalm of David... but it's a psalm of David now, when David is St. David in Heaven around the Throne of the Lord Most High. Now, thanks to Jesus, he can truly say "My steps have kept to your paths" and "I am just". And now, as he awaits the bodily resurrection to come for us all, now he can pray (in verse 15): "When I awake, let me be filled with your presence."