Today’s lectionary has very little to mention topically — I have found a whole pile of links to odd things that are happening, but that is not really the issue.
There are two parts to this passage, and both are equally important.
13Then little children were being brought to him in order that he might lay his hands on them and pray. The disciples spoke sternly to those who brought them; 14but Jesus said, “Let the little children come to me, and do not stop them; for it is to such as these that the kingdom of heaven belongs.” 15And he laid his hands on them and went on his way.
16Then someone came to him and said, “Teacher, what good deed must I do to have eternal life?” 17And he said to him, “Why do you ask me about what is good? There is only one who is good. If you wish to enter into life, keep the commandments.” 18He said to him, “Which ones?” And Jesus said, “You shall not murder; You shall not commit adultery; You shall not steal; You shall not bear false witness; 19Honor your father and mother; also, You shall love your neighbor as yourself.” 20The young man said to him, “I have kept all these; what do I still lack?” 21Jesus said to him, “If you wish to be perfect, go, sell your possessions, and give the money to the poor, and you will have treasure in heaven; then come, follow me.” 22When the young man heard this word, he went away grieving, for he had many possessions.
The first part is that the gospel is simple, and the worship of a child is valid. You do not need to have an abstruse theological knowledge to be a Christian. A child like faith can grow.
The second is that our sense of being legal: of doing things that are correct in law is not enough. We can keep the external law, but each of us knows that our heart is full of desires which are not. The old monks described seven deadly sins for a reason: you may be celibate but wrathful, peaceful but covetous. Instead it is going to the point where, like a child, the love of Christ is overwhelming.
In the end, before God, we are all as children. To see yourself otherwise is to delude yourself. The law is a teacher, but the law will condemn us. It is not sufficient, and it will never be sufficient.
For that we have Christ.