This chapter seems to me to give more the grace of the Lord's ways, and what was coming in, the Spirit in which they had to walk, in which He did. Chapter 20, the sounding all the motives of the human heart, and breaking with all that tied to earth and was valued there, only fully sanctioning all that God had established in nature, all that was amiable in His creation. But now there was none good but God, and, while bringing in a power that lifted above and out of all that acted on or kept nature, yet, as I have said, sanctioned all God had originally established. It is remarkable in this respect. The ordinances, as marriage, etc., were good in themselves. If a man wanted to enter into life, he was to keep the commandments. But creation goodness morally was gone. None—no person was good but God. And, if we want to go wholly with Him, we must have done wholly with the world, and break with the system flesh has formed round itself.
In this chapter humility is taught as well as goodness. Verses 6-9 are a kind of warning parenthesis. How to deal with personal wrong in the new state of things is provided for. Judgment of self, and patient goodness with others is the rule, with provision in the Church for obstinate wrong. The whole, in general (save this special ordering within) is the kingdom of heaven, and goes on to consequent place in the regeneration.
In what is first addressed to the young man, we have the external positive responsibility of man, then the fact that none is good but God—the real truth, so to speak—and the judgment of the heart in motives, and hence self-sacrifice. These are the great moral questions, and the difference of law and Christian practice. With this, reward connects itself, and here He speaks of everlasting life.