“And the Lord has rewarded me according to my righteousness, according to my cleanness in his sight.” (ESV – Read the chapter)
What David says right here reflects a pre-Jesus understanding of how God operates toward us that is rooted in the Mosaic Covenant. Under that system, if someone kept the Law or at least had offered the proper sacrifices, they could consider themselves clean before God. And God allowed this to be the case even though they weren’t totally right. Their sins had been covered, but they weren’t forgiven. Once Jesus came, He revealed David’s thinking to be right, but his confidence to be very much wrong.
Remember, the David writing this is the same David we’ve spent the past several chapters looking at how thoroughly he blew it with Bathsheba and Uriah and the fallout from that. For him to boast of his righteousness and cleanness in the sight of God seems pretty bold. But, according to the Old Covenant system, he could say as much. If he had purified himself by the appropriate sacrifices, then according to the Law, he was clean and his righteousness had been restored.
The deeper truth, as Jesus and in particular the author of Hebrews would make clear, is that an animal sacrifice can’t possibly remove the sins of a person because there isn’t the necessary one-to-one correspondence. God accepted the animal sacrifice because He is a God of mercy and love, but we needed a better system to really get the job done.
That’s why David’s confident tone is misplaced. But, I also said his thinking was correct. How’s that? Because God will indeed reward us according to our righteousness (or lack thereof). The final judgment will be based entirely on our works. This is why groups like the Pharisees formed who were so fanatical and legalistic about keeping the Law. If judgment was to be based on our righteousness, and if none are righteous, no, not one (something David was actually recorded first as saying), then we’ve got to be as careful as we possibly can to keep every single piece and part of the Law.
Unfortunately, as Jesus made clear in Matthew 5, even the righteousness of the Pharisees isn’t going to be enough to get the job done, to make us righteous enough for God.
What we need is someone else’s righteousness who actually got the job done to cover over ours so we look a whole lot better than we actually are. Well, in Christ, that’s exactly what we have. When we place ourselves in Jesus by faith, when we accept as efficacious His work on the cross on our behalf, when we place ourselves under His lordship and commit to following Him, He places His righteousness over us like a coat. From then on, any time God looks at us, He sees Jesus, and pronounces us clean to be in His presence. And, because we can be in His presence, we can receive the life that only comes from Him.
If you’re trying to be good enough for God on your own, quit it. You’re not going to get there. No amount of effort will ever get the job done and you’ll make yourself an unbearable, legalistic, jerk along the way. Trust in Jesus. He’s the way to get where you’re trying to go.