A young man approached Jesus and said,
“Teacher, what good must I do to gain eternal life?”
He answered him, “Why do you ask me about the good?
There is only One who is good.
If you wish to enter into life, keep the commandments.”
He asked him, “Which ones?”
And Jesus replied, “You shall not kill;
you shall not commit adultery;
you shall not steal;
you shall not bear false witness;
honor your father and your mother;
and you shall love your neighbor as yourself.”
The young man said to him,
“All of these I have observed. What do I still lack?”
Jesus said to him, “If you wish to be perfect, go,
sell what you have and give to the poor,
and you will have treasure in heaven.
Then come, follow me.”
When the young man heard this statement, he went away sad,
for he had many possessions.
19:16 Gain eternal life: this is equivalent to “entering into life” (Mt 19:17) and “being saved” (Mt 19:25); the life is that of the new age after the final judgment (see Mt 25:46). It probably is also equivalent here to “entering the kingdom of heaven” (Mt 19:23) or “the kingdom of God” (Mt 19:24).
19:17 By Matthew’s reformulation of the Marcan question and reply (Mk 10:17–18) Jesus’ repudiation of the term “good” for himself has been softened. Yet the Marcan assertion that “no one is good but God alone” stands, with only unimportant verbal modification.
19:18–19 The first five commandments cited are from the Decalogue (see Ex 20:12–16; Dt 5:16–20). Matthew omits Mark’s “you shall not defraud” (Mk 10:19; see Dt 24:14) and adds Lv 19:18. This combination of commandments of the Decalogue with Lv 19:18 is partially the same as Paul’s enumeration of the demands of Christian morality in Rom 13:9.
19:20 Young man: in Matthew alone of the synoptics the questioner is said to be a young man; thus the Marcan “from my youth” (Mk 10:20) is omitted.
19:21 If you wish to be perfect: to be perfect is demanded of all Christians; see Mt 5:48. In the case of this man, it involves selling his possessions and giving to the poor; only so can he follow Jesus.
“The question which the rich young man puts to Jesus of Nazareth is one which rises from the depths of his heart. It is an essential and unavoidable question for the life of every man, for it is about the moral good which must be done, and about eternal life. The young man senses that there is a connection between moral good and the fulfillment of his own destiny. He is a devout Israelite, raised as it were in the shadow of the Law of the Lord. If he asks Jesus this question, we can presume that it is not because he is ignorant of the answer contained in the Law. It is more likely that the attractiveness of the person of Jesus had prompted within him new questions about moral good. He feels the need to draw near to the One who had begun his preaching with this new and decisive proclamation: ‘The time is fulfilled and the Kingdom of God is at hand; repent, and believe in the Gospel’ (Mark 1:15).”
– Saint Pope John Paul II, Encyclical Letter, Veritatis Splendor 8