The following is an excerpt from The MacArthur New Testament Commentary on John 3.

Nicodemus said to Him, “How can a man be born when he is old? He cannot enter a second time into his mother’s womb and be born, can he?” Jesus answered, “Truly, truly, I say to you, unless one is born of water and the Spirit he cannot enter into the kingdom of God. That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. Do not be amazed that I said to you, ‘You must be born again.’ The wind blows where it wishes and you hear the sound of it, but do not know where it comes from and where it is going; so is everyone who is born of the Spirit.” (3:4–8)

Jesus’ shocking statement was far more than Nicodemus had expected. Incredulous, Nicodemus said to Him, “How can a man be born when he is old? He cannot enter a second time into his mother’s womb and be born, can he?” Certainly, this highly educated Pharisee was not so obtuse as to have misinterpreted Jesus’ words in a simplistically literal sense. He knew our Lord was not talking about being physically reborn, but he replied in the context of the Lord’s analogy. How could he start all over, go back to the beginning? Jesus was telling him that entrance to God’s salvation was not a matter of adding something to all his efforts, not topping off his religious devotion, but rather canceling everything and starting all over again. At the same time, he clearly could not grasp the full meaning of what that meant. His questions convey his confusion, as he openly wondered at the impossibility of Christ’s statement. Jesus was asking for something that was not humanly possible (to be born again); He was making entrance into the kingdom contingent on something that could not be obtained through human effort. But if that was true, what did it mean for Nicodemus’s works-based system? If spiritual rebirth, like physical rebirth, was impossible from a human standpoint, then where did that leave this self-righteous Pharisee?

Far from minimizing the demands of the gospel, Jesus confronted Nicodemus with the most difficult challenge He could make. No wonder Christ would later say to His disciples, “Children, how hard it is to enter the kingdom of God!” (Mark 10:24). By calling him to be born again, Jesus challenged this most religious Jew to admit his spiritual bankruptcy and abandon everything he was trusting in for salvation. That is precisely what Paul did, as he declared in Philippians 3:8–9:

More than that, I count all things to be loss in view of the surpassing value of knowing Christ Jesus my Lord, for whom I have suffered the loss of all things, and count them but rubbish so that I may gain Christ, and may be found in Him, not having a righteousness of my own derived from the Law, but that which is through faith in Christ, the righteousness which comes from God on the basis of faith.

Jesus answered Nicodemus’s confusion by elaborating on the truth He introduced in verse 3: “Truly, truly, I say to you, unless one is born of water and the Spirit he cannot enter into the kingdom of God.” A number of interpretations have been offered to explain the phrase born of water. Some see two births here, one natural, and the other spiritual. Proponents of this view interpret the water as the amniotic fluid that flows from the womb just before childbirth. But it is not clear that the ancients described natural birth in that way. Further, the phrase born of water and the Spirit parallels the phrase “born again” in verse 3; thus, only one birth is in view. Others see in the phrase born of water a reference to baptism, either that of John the Baptist, or Christian baptism. But Nicodemus would not have understood Christian baptism (which did not yet exist) nor misunderstood John the Baptist’s baptism. Nor would Jesus have refrained from baptizing people (4:2) if baptism were necessary for salvation. Still others see the phrase as a reference to Jewish ceremonial washings, which being born of the Spirit transcends. However the two terms are not in contrast with each other, but combine to form a parallel with the phrase “born again” in verse 3. (For a careful examination of the various interpretations of born of water, see D. A. Carson, The Gospel According to John, The Pillar New Testament Commentary [Grand Rapids: Eerdmans, 1991], 191–96.)

Since Jesus expected Nicodemus to understand this truth (v. 10), it must have been something with which he was familiar. Water and Spirit often refer symbolically in the Old Testament to spiritual renewal and cleansing (cf. Num. 19:17–19; Isa. 4:4; 32:15; 44:3; 55:1; Joel 2:28–29; Zech. 13:1). In one of the most glorious passages in all of Scripture describing Israel’s restoration to the Lord by the new covenant, God said through Ezekiel,

For I will take you from the nations, gather you from all the lands and bring you into your own land. Then I will sprinkle clean water on you, and you will be clean; I will cleanse you from all your filthiness and from all your idols. Moreover, I will give you a new heart and put a new spirit within you; and I will remove the heart of stone from your flesh and give you a heart of flesh. I will put My Spirit within you and cause you to walk in My statutes, and you will be careful to observe My ordinances. (Ezek. 36:24–27)

It was surely this passage that Jesus had in mind, showing regeneration to be an Old Testament truth (cf. Deut. 30:6; Jer. 31:31–34; Ezek. 11:18–20) with which Nicodemus would have been acquainted. Against this Old Testament backdrop, Christ’s point was unmistakable: Without the spiritual washing of the soul, a cleansing accomplished only by the Holy Spirit (Titus 3:5) through the Word of God (Eph. 5:26), no one can enter God’s kingdom.

Jesus continued by further emphasizing that this spiritual cleansing is wholly a work of God, and not the result of human effort: “That which is born of the flesh is flesh, and that which is born of the Spirit is spirit.” Just as only human nature can beget human nature, so also only the Holy Spirit can effect spiritual transformation. The term flesh (sarx) here refers merely to human nature (as it does in 1:13–14); in this context, it does not have the negative moral connotation that it frequently does in Paul’s writings (e.g., Rom. 8:1–8, 12–13). Even if a physical rebirth were possible, it would produce only flesh. Thus, only the Spirit can produce the spiritual birth required for entrance into God’s kingdom. Regeneration is entirely His work, unaided by any human effort (cf. Rom. 3:25).

Although Jesus’ words were based on Old Testament revelation, they ran completely contrary to everything Nicodemus had been taught. For his entire life he had believed that salvation came through his own external merit. Now he found it exceedingly difficult to think otherwise. Aware of his astonishment, Jesus continued, “Do not be amazed that I said to you, ‘You must be born again.’ ” The verb translated must is a strong term; John used it elsewhere in his gospel to refer to the necessity of the crucifixion (3:14; 12:34), of John the Baptist’s inferiority to Christ (3:30), of the proper method of worshiping God (4:24), of Jesus carrying out His ministry (4:4; 9:4; 10:16), and of the necessity of the resurrection (20:9). It was absolutely necessary for Nicodemus to get over his astonishment at being so wrong about how one is accepted into God’s kingdom and seek to be born again if he was to enter. And he could never do so based on his own righteous works.

Then the Lord illustrated His point with a familiar example from nature: “The wind blows where it wishes and you hear the sound of it, but do not know where it comes from and where it is going; so is everyone who is born of the Spirit.” The wind cannot be controlled; it blows where it wishes. And though its general direction can be known, where it comes from and where it is going cannot be precisely determined. Nevertheless, the wind’s effects can be observed. The same is true of the work of the Spirit. His sovereign work of regeneration in the human heart can neither be controlled nor predicted. Yet its effects can be seen in the transformed lives of those who are born of the Spirit.