Jesus wanted the man to think about the word he had just used so freely. If only God is truly good, then calling someone "good" is a serious claim. Barnes says it was probably a title the Jews used for their religious teachers, a complimentary or flattering title, and that "Christ did not intend here to disclaim divinity, or to say anything about his own character, but simply to reprove the intention and habit of the young man." Gill says Jesus spoke this way "because this young man considered him only as a mere man." Gill adds that Jesus was good both as God and as man, and did not deny it. The question also prepares for the rest of the answer: if none is good but God, then no one can do enough good to earn eternal life.

The young man does not answer the question about why he called Jesus good. He asks a question of his own: "Which?" (Matthew 19:18), meaning which commandments. Jesus lists them, and the man replies, "All these things have I kept from my youth up: what lack I yet?" (Matthew 19:20). His confidence in his own goodness is then tested when Jesus tells him to sell what he has and follow Him, and he goes away sorrowful (Matthew 19:21-22).

The KJV and ESV read differently here because they follow different Greek texts. The Textus Receptus behind the KJV reads Ti me legeis agathon, "Why do you call me good?", matching Mark 10:18 and Luke 18:19. Other manuscripts read "Why do you ask me about what is good?", which the ESV follows.

"Keep the commandments" points to the Law of Moses. Barnes explains why Jesus said it: "to try him, and to convince him that he had by no means kept the commandments." Gill says, "Our Lord answers according to the tenor of the covenant of works," to show that it is impossible to obtain eternal life by the works of the law.

This question is about God's character. "There is none good but one, that is, God." Goodness is not a polite title. It belongs to God. When someone calls Jesus good, the honest question is whether they understand what they are saying.

Jesus does not deny that He is good. He asks the man to think. The story that follows shows why it matters. The man thinks of himself as good enough to have kept the law (Matthew 19:20), yet he cannot let go of his possessions to follow the One he called good (Matthew 19:22). Only God is good, and only God can save (Matthew 19:26).