“For, being ignorant of the righteousness of God, and seeking to establish their own, they did not submit to God’s righteousness.” (ESV)
Paul’s argument here is that while the Jewish people were striving to be in a right relationship with God (that is, to obtain righteousness), they were going about it as if that relationship depended on them, not God. They had taken the Law of Moses, which God had given them to help them along the path of righteousness by showing them where some of the boundaries of a relationship with Him were, and essentially turned it on its head. Instead of using the Law to lead them to the place where they recognized their need to depend totally on God for help at staying within the boundaries of a relationship with Him, they used it as an exact description of what they needed to do themselves in order to achieve such a relationship. And, where the Law wasn’t exact enough, they made it even more so.
Now, it’s true that had anyone been able to keep the Law perfectly, as Jesus did, they would have remained in a right relationship with God. But that’s only if they had done so from birth and never strayed outside the lines even once. Because of sin, though, that is a standard no one has or will ever achieve. Except for Jesus.
What’s more, because leaving the bounds of a relationship with God is to steal our lives from Him (our lives are His because He made us and thus owns us), in order to cross back into those boundaries we need to give back what we took: Our lives. Well, if we give our lives to God, we don’t have them anymore. If we don’t have life, then we have death. To get back into a relationship with God after having left it for any reason would have cost us each our lives.
This is what the Jews didn’t understand. They believed that by keeping the Law perfectly they could get themselves back across the lines of a relationship with God and achieve righteousness. This would come, not because of something God did, but rather because of what they did. This was a works-based, self-righteousness. They didn’t understand that this would have been their righteousness, not God’s. They also didn’t understand the purpose of the Law was not to be a guide for how to achieve righteousness, but a description of what it looks like to have it. It’s a description that points us to the necessity of faith in Him for help in remaining on the inside of the boundaries.
This has always been the challenge of the Gospel, but also its wonder. We don’t have righteousness on our own and no amount of effort on our part will ever bring us to that point. Our attempts at righteousness will never reach even close to the level of God’s righteousness. God knew this and so He reached out when we were still sinners, sending His Son to live a life of perfect righteousness and give His life to God on our behalf so that we could get back across the boundaries of a relationship with Him, and granting us a share in Christ’s righteousness so we could stay there.
When we are willing to submit to this, we will enjoy righteousness and eternal life. If we aren’t, we won’t. That there is absolutely only one path to righteousness which does not depend even a little bit on our effort is hard for us to accept even as it was hard for Paul’s audience, but there is hope in that it is absolutely open to everyone without exceptions or distinctions. We need only take it and make sure folks around us know about it.