Matthew 18: How to enter in the kingdom of heaven?

We don't read so much things like: "accept Jesus" or "when were you converted?" in the gospels and even in the roman catholic church. However, we read in MSG:

2-5 For an answer Jesus called over a child, whom he stood in the middle of the room, and said, “I’m telling you, once and for all, that unless you return to square one and start over like children, you’re not even going to get a look at the kingdom, let alone get in. Whoever becomes simple and elemental again, like this child, will rank high in God’s kingdom. What’s more, when you receive the childlike on my account, it’s the same as receiving me.


The values of this world are the opposite of the values in the kingdom: the king of this world is the one who is served but the King in the kingdom of heaven is the one who not only serves, but also give his life as food for their servants.  Therefore, to enter in the kingdom is necessary a conversion, a change in priorities. This change is not easy for any human being, but it is the work of the Spirit who makes one person start over like children: everything has to be learned again.

To learn means to recognize errors and improve. A Christian is not someone perfect, but a one who walks with Christ, who learns with Jesus. As he is not perfect, the kingdom of heaven, the church must help him, forgive him and teach him. We read:

15-17 “If a fellow believer hurts you, go and tell him—work it out between the two of you. If he listens, you’ve made a friend. If he won’t listen, take one or two others along so that the presence of witnesses will keep things honest, and try again. If he still won’t listen, tell the church. If he won’t listen to the church, you’ll have to start over from scratch, confront him with the need for repentance, and offer again God’s forgiving love.

It is really strange and marvelous that the kingdom of heaven is made of sinners who are constantly repenting.