All Christians believe in the spiritual world and the existence of spiritual beings. God is spirit, and if you believe in God, you also believe in the world he lives and exists in. Such a world, however, is still a mystery and unknown to us who live in the physical world. Some believe it exists, or know it must exist, but its existence cannot be proved with science, nor measured with experiments. Does it really exist? If it does, how do we know it does?

One day, a man of the Pharisees came to Jesus at night, and said:

Rabbi, we know you are a teacher who has come from God. For no one could perform the miraculous signs you are doing if God were not with him (John 3:2).

This man’s name was Nicodemus, and he was one of the rulers of Israel. Hearing about Jesus, or perhaps seeing him perform miracles, he got interested in him. He thought Jesus must have come from God because of the miracles he was doing. So, Nicodemus, being a good Pharisee, was honest enough to admit that Jesus was sent from God. But to our surprise, Jesus said to him:

I tell you the truth, no one can see the kingdom of God unless he is born again (v. 3).

Now, being a member of the Jewish ruling council, he too was seriously looking forward to the coming of God’s kingdom. He was proud of being in the forefront of this movement, and he thought that he would be among the first ones to see God’ kingdom come when it actually did. So, it must have been quite a shock for him to hear Jesus say, “no one can see the kingdom of God unless he is born again” because he understood that Jesus meant, “you cannot see it, and will not see it.” Furthermore, he wondered what Jesus meant by “unless he is born again.” He said:

How can a man be born when he is old?　Surely he cannot enter a second time into his mother's womb to be born (v. 4)!

It was a very straight and honest question. People who ask such questions will grow up spiritually. It indicates that they are thinking and trying to understand what God’s word means. Christians often think that asking questions about the Bible is a mark of doubts on God’s word, and they are afraid of asking or being asked. God’s thoughts are not like our thoughts, and as the heavens are higher than the earth, so are his thoughts higher than our thoughts. If so, we will have many questions about his thoughts. It is good to ask, and he is glad to answer us. Amen!

So, Jesus answered:

I tell you the truth, no one can enter the kingdom of God unless he is born of water and the Spirit. Flesh gives birth to flesh, but the Spirit gives birth to spirit. You should not be surprised at my saying, “You must be born again (vv. 5-7).”

“Flesh” here is of a physical kind in a narrow sense. “Flesh gives birth to flesh, but the Spirit gives birth to spirit.” In other words, entering into the mother’s womb is of the flesh, but being born again is of the spirit. And in order to see the kingdom of God, one must be born of the Spirit, which indicates that this kingdom is of a spiritual kind. Here, Jesus spoke of the two separate and independent worlds—one is physical and the other is spiritual.