Let us start with the Kingdom of Heaven. What does this mean? We get our best defination of it from the Lord’s Prayer. There are two petitions side by side:
Thy Kingdom come: Thy will be done in earth as it is in heaven.
It is characteristic of Jewish style to say things twice, the second way explaining and amplifying the first. Any verse of the Psalms will show us this Jewish habit of what is technically known as parallelism:
The Lord of hosts is with us:
The God of Jacob is our refuge (Psalm 46: 7).

For I know my transgressions:
And my sin is ever before me (Psalm 51:3).

He makes me lie down in green pastures:
He leads me beside still waters (Psalm 23:2).

Let us apply that principle to these two petitions in the Lord's Prayer. The second petition amplifies and explains the first; we then arrive at the definition: the kingdom of heaven is a society where God's will is as perfectly done on earth as it is in heaven. To be in the kingdom of heaven is therefore to lead a life in which we have willingly submitted everything to the will of God; it is to have arrived at a stage when we perfectly and completely accept the will of God.

Now let us take sonship. In one sense sonship is a tre¬mendous privilege. To those who believe there is given the power to become sons (John 1: 12). But the very essence of sonship is necessarily obedience." He who has commandments, and keeps them, he it is who loves me " (John 14: 21). The essence of sonship is love; and the essence of love is obedience.
We cannot with any reality say that we love a person and then do things which hurt and grieve that person's heart. Sonship is a privilege, but a privilege which is entered into only when full: obedience is given. So then to be a son of God and to be in the kingdom are one and the same thing. The son of God and the citizen of the kingdom are both people who have completely, and willingly accepted the will of God.

Now let us take eternal life. It is far better to speak of eternal life than to speak of everlasting life. The main idea behind eternal life is not simply that of duration. It is quite clear that a life which went on for ever could just as easily be hell as heaven. The idea behind eternal life is the idea of a certain quality of life. What kind? There is only one person who can properly be described by this adjective eternal (aidnios) and that one person is God. Eternal life is the kind of life that God lives; it is God's life . To enter into eternal life is to enter into possession of that kind of life which is the life of God. It is to be lifted up above merely human, transient things into that joy and peace which belong only to God. Clearly a man can enter into this close fellowship with God only when he renders to him that love, that reverence, that devotion, that obedience which truly bring him into fellowship with him.

Here then we have three great kindred conceptions, entry into the kingdom of heaven, sonship of God and eternal life; and all are dependent on and are the products of perfect obedience to the will of God. It is just here that the idea of being reborn comes in. It is what links all these three conceptions together. It is quite clear that, as we are and in our own strength, we are quite unable to render to God this perfect obedience; it is only when God's grace enters into us and takes possession of us and changes us that we can give to him the reverence and the devotion we ought to give. It is through Jesus Christ that we are reborn; it is when he enters into possession of our hearts and lives that the change comes.

When that happens we are born of water and the Spirit.
There are two thoughts there. Water is the symbol of cleansing. When Jesus takes possession of our lives, when we love him with all our heart, the sins of the past are forgiven and forgotten. The Spirit is the symbol of power. When Jesus takes possession of our lives it is not only that the past is forgotten and forgiven; if that were all, we might well proceed to make the same mess of life all over again; but into life there enters a new power which enables us to be what by ourselves we could never be and to do what by ourselves we could never do. Water and the Spirit stand for the cleansing and the strengthening power of Christ, which wipes out the past and gives victory in the future.

Finally, in this passage, John lays down a great law. That which is born of the flesh is flesh and that which is born of the Spirit is spirit. A man by himself is flesh and his power is limited to what the flesh can do. By himself he cannot be other than defeated and frustrated; that we know only too well; it is the universal fact of human experience. But the very essence of the Spirit is power and life which are beyond human power and human life; and when the Spirit takes possession of us, the defeated life of human nature becomes the victorious life of God.

To be born again is to be changed in such a way that it can be described only as rebirth and re-creation. The change comes when we love Jesus and allow him into our hearts. Then we are forgiven for the past and armed by the Spirit for the future; then we can truly accept the will of God. And then we become citizens of the kingdom; then we become sons of God; then we enter into eternal life, which is the very life of God.

Verses 7-13

There are two kinds of misunderstanding. There is the mis¬understanding of the man who misunderstands because he has not yet reached a stage of knowledge and of experience at which he is able to grasp the truth. When a man is in that state, our duty is to do all that we can to explain things to him so that he will be able to grasp the knowledge which is being offered to him. There is also the misunderstanding of the man who is unwilling to understand or refusal to see. A man can deliberately shut his mind to truth which he does not wish to accept.

Nicodemus was like that. The teaching about a new birth from God should not have been strange to him. Ezekiel, for instance, had spoken repeatedly about the new heart that must be created in a man. " Cast away from you all the trans¬gressions, which you have committed against me, and get yourselves a new heart and a new spirit! Why will you die, O house of Israel?" (Ezekiel 18: 31) "A new heart I will give you, and a new spirit I will put within you " (Ezekiel 36: 26). Nicodemus was an expert in scripture and again and again the prophets had spoken of that very experience of which Jesus was speaking. If a man does not wish to be reborn, he will deliberately misunderstand what rebirth means. If a man does not wish to be changed, he will deliberately shut his eyes and his mind and his heart to the power which can change him. In the last analysis what is the matter with so many of us is simply the fact that, when Jesus Christ comes with his offer to change us and re-create us, we more or less say: " No thank you: I am quite satisfied with myself as I am, and I don't want to be changed."

Nicodemus was driven back on another defence. In effect he said: " This rebirth about which you talk may be possible; but I can't understand how it works." The answer of Jesus depends for its point on the fact that the Greek word for spirit, pneuma, has two meanings. It is the word for spirit, but it is also the regular word for wind. The same is true of the Hebrew word ruach; it too means both spirit and wind. So Jesus said to Nicodemus: "You can hear and see and feel the wind (pneuma); but you do not know where it comes from or where it is going to. You may not understand how and why the wind blows; but you can see what it does. You may not understand where a gale came from or where it is going to, but you can see the trail of flattened fields and uprooted trees that it leaves behind it. There are many things about the wind you may not understand; but its effect is plain for all to see." He went on, " the Spirit ipneuma) is exactly the same. You may not know how the Spirit works; but you can see the effect of the Spirit in human lives."

Jesus said: " This is no theoretical thing of which we are speaking. We are talking of what we have actually seen. We can point to man after man who has been re-born by the power of the Spirit."

There are any number of things in this world which we use every day without knowing how they work. Comparatively few of us know how electricity or radio or television works; but we do not deny that they exist because of that. Many of us drive a motor car with only the haziest notion of what goes on below its bonnet; but our lack of understanding does not prevent us using and enjoying the benefits which a motor car confers. We may not understand how the Spirit works; but the effect of the Spirit on the lives of men is there for all to see. The unanswer¬able argument for Christianity is the Christian life. No man can disregard a faith which is able to make bad men good.

Jesus said to Nicodemus: " I have tried to make things simple for you; I have used simple human pictures taken from everyday life; and you have not understood. How can you ever expect to understand the deep things, if even the simple things are beyond you? " There is a warning here for every one of us. It is easy to sit in discussion groups, to sit in a study and to read books, it is easy to discuss the intellectual truth of Christianity; but the essential thing is to experience the power of Christianity. And it is fatally easy to start at the wrong end and to think of Christianity as something to be discussed, not as something to be experienced. It is certainly important to have an intellectual grasp of the orb of Christian truth; but it is still more important to have a vital experience of the power of Jesus Christ. When a man undergoes treatment from a doctor, when he has to have an operation, when he is given some medicine to take, he does not need to know the anatomy of the human body, the scientific effect of the anaesthetic, the way in which the drug works on his body, in order to be cured. Ninety-nine men out of every hundred accept the cure with¬out being able to say how it was brought about. There is a sense in which Christianity is like that. At its heart there is a mystery, but it is not the mystery of intellectual appreciation; it is the mystery of redemption.

In reading the Fourth Gospel there is the difficulty of knowing when the words of Jesus stop and the words of the writer of the gospel begin. John has thought so long about the words of Jesus that insensibly he glides from them to his own thoughts about them. Almost certainly the last words of this passage are the words of John. It is as if someone asked: " What right has Jesus to say these things? What guarantee do we have that they are true? " John's answer is simple and profound. " Jesus," he says," came down from heaven to tell us the truth of God." It was John's conten¬tion that Jesus's right to speak came from the fact that he knew God personally, that he had come direct from the secrets of heaven to earth, that what he said to men was most literally God's own truth, for Jesus was and is the embodied mind of God.