It is instructive to see that Luke places this incident directly following Jesus giving thanks to His Father, “that you have hidden these things from the wise and understanding and revealed them to little children”. The “little children” are Jesus’ disciples, His followers, who have just learned about spiritual power in His name. Now we meet the lawyer, one of the “wise and understanding”, a scholar schooled in all the intricacies and interpretations of the Old Testament Law. The children and wise are placed in sharp contrast.
The lawyer asks an important question, which is really the ultimate question, “what shall I do to inherit eternal life?” but he has an underlying motive. He was testing Jesus to see if He could trip Him up, make Him contradict Himself, or contradict the Law, perhaps ultimately trying to prove that His claims to be the Son of God were demonstrably false. Instead of answering the man, Jesus turns the question back on him, appealing to his self-perception of being an authority. The one who came to test is now being tested.
The lawyer was trying to set Jesus up so as to take Him down. But Jesus was setting him up so as to take down his self-righteousness. Jesus agrees that his answer describes the essence of the Law (Leviticus 19:18 / Deuteronomy 6:4-5 / Matthew 7:12, 22:35-40 / Mark 12:28-34 / Romans 13:8-10 / Galatians 5:14 / James 2:8-10). Jesus says that if the man does this he will indeed inherit eternal life.
The problem is that no one can fulfill this requirement. The lawyer was rich in knowledge, and thought this meant he could achieve, accomplish, attain whatever it took to gain favor with God. In contrast, the disciples knew they were nothing without Jesus. They were learning true knowledge, not to be proud in their own selves, but to give glory to God.
You may grow and learn and be about all those good things you ought to do, but you mustn’t let those things make you think you are now somehow less needing of mercy and grace. You may be rich in your relationship with God, but that means you realize your poverty without Him.
Don’t be some smug wise guy, thinking you have it all figured out. Realize what Jesus meant when He said, “Blessed are the poor in spirit”.