What does Romans 2:23 mean?

Paul has been asking a series of rhetorical questions. Now, he states his point with complete clarity. He is correcting the misperception of some religious Jews. By extension, this idea also applies to any person—Jewish, Christian, or otherwise—who thinks he can be justified before God on the basis of his deeds. The specific people Paul mentions here apparently believed that having the law of Moses, given by God, was enough to make them righteous in God's eyes. They didn't believe God would judge them for their sin as He would the sinful Gentiles.

Paul has shown that having the law is not enough if you don't perfectly keep the law. He will go on in Romans to show that nobody can keep the law to that extent (Romans 3:10). Instead, everyone who is under the authority of the law ends up dishonoring God by breaking it. How can a holy God ignore sin, simply because a person sometimes does good?