Paul is talking about his own background as someone who tried very hard to do what God wanted, but without Jesus. He felt like if he really worked at it, he could earn God’s favor. But that only led to frustration because he could never be good enough. In fact, the better he tried to be, the worse he felt he was doing. What he needed was Jesus, but it took him some time to figure that out.
Some people come to Jesus after having made a mess of their own lives. They wonder how God could forgive someone as bad as they are. Some are like Paul and come to Jesus after having lived really good lives and trying to earn God’s love. They wonder why someone so good would need forgiveness. Ironically, it’s the good ones who are the hardest to convince. Which one were, or are, you?