18A certain ruler asked him, "Good teacher, what must I do to inherit eternal life?" 19"Why do you call me good?" Jesus answered. "No one is good—except God alone. 20You know the commandments: 'Do not commit adultery, do not murder, do not steal, do not give false testimony, honor your father and mother." 21"All these I have kept since I was a boy," he said. 22When Jesus heard this, he said to him, "You still lack one thing. Sell everything you have and give to the poor, and you will have treasure in heaven. Then come, follow me." 23When he heard this, he became very sad, because he was a man of great wealth (Luke 18:18-23).
Few of the religious rulers had any time for Christ, yet this man felt compelled to get an interview with Jesus. He was so passionate about finding eternal life that Mark tells us in a parallel passage that he ran up to Jesus and fell on his knees before Him (Mark 10:17). He said, "Good teacher, what must I do to inherit eternal life?" One of Satan's schemes to deceive a man from turning to Christ is to have him look for things he can do to please God. People hope that God will see how hard they are trying to please Him and reward our good works by opening the door of the kingdom to us. Satan enjoys watching us trying to please God with good works. He is the master of deception. This man had no assurance of salvation even though he had worked hard all his young life to try to gain peace with God. Before a man can receive the Kingdom of God, he must first see how far short of the kind of life God requires. The standard God demands is perfection:
Be perfect, therefore, as your heavenly Father is perfect (Matthew 5:48).
Our problem is that we are sinners by nature and fall far short of the standard God requires. We are not sinners because we sin; we sin because we are sinners. It is in our very nature to sin. No matter how good a person thinks he is, just one sin makes us fall short of perfection and needful of God’s grace and mercy.
For whoever keeps the whole law and yet stumbles at just one point is guilty of breaking all of it (James 2:10).
God gave the Law and Commandments as a means for us to see how far we have transgressed over the line into sin. How would we know what sin was without the Ten Commandments? Paul, the apostle, wrote: "no one will be declared righteous in his sight by observing the law, rather through the law, we become conscious of sin" (Romans 3:20). The importance of the law cannot be overstated. How will a person seek the Savior if he is not convinced of his need? Presenting the gospel with no accompanying message of how a person has fallen short of God's glory seriously minimizes the message of the gospel to a person's heart. A person loves much when he sees how much he has been forgiven. Jesus stated it like this: “He who has been forgiven little loves little” (Luke 7:47). The greater our perception of our personal sin to a holy God, the greater will be our love response when we are forgiven. God is looking for a love relationship with those who turn to Him. We have an inner voice, our conscience, that tells us that what we are about to do is wrong before we do it. It punishes us as a judge if we do not listen and continue in sin. The Internal Revenue Service (Tax Dept) received the following letter from a conscience-stricken taxpayer:
“Dear Sir: My conscience bothered me. Here is $175.00, which I owe in back taxes.” There was a P.S. at the bottom that read: “If my conscience still bothers me, I’ll send in the rest.”
This rich young man’s conscience was bothering him. John Trapp said: “Conscience is God’s spy and man’s overseer.” Jesus pointed the rich ruler back to the commandments so that he could see how far short he fell. Shrugging off his conscience, he claimed to have kept the commandments since he was a boy, but still, something was missing. The Lord saw his heart as only God can and told him to sell all he had and give it to the poor.
This rich young ruler’s problem was that he loved things more than he loved God. The Lord considered his soul and saw that he was holding something back and that it was keeping him from surrendering his life to God. God wants to kick away every crutch we lean on until we rely on the finished work of Christ. Christianity is not a crutch; it is a wheelchair—we lean our total trust on Him alone. The rich man walked away, shoulders slumped, face downcast, because he relied on his riches. There is rest for our souls when nothing is held back or kept in reserve, and we lean only on Christ. Don't let anything hold you back from total abandonment to Jesus. He will be there to support you. That is the essence of faith. Keith Thomas
Taken from the in-depth study, The Rich Ruler in the Gospel of Luke found here
 1500 Illustrations for Biblical Preaching, Michael P. Green, Page 79.