In our Lord's _language_ there was nothing that need have puzzled Nicodemus. In religious circles in Jerusalem there was nothing being talked of but the kingdom of God which John the Baptist had declared to be at hand. And when Jesus told Nicodemus that in order to enter this kingdom he must be born again, He told him just what John had been telling the whole people. John had assured them that, though the King was in their midst, they must not suppose they were already within His kingdom by being the children of Abraham. He excommunicated the whole nation, and taught them that it was something different from natural birth that gave admission to God's kingdom. And just as they had compelled Gentiles to be baptized, and to submit to other arrangements when they wished to partake of Jewish privileges, so John compelled them to be baptized. The Gentile who wished to become a Jew had to be symbolically born again. He had to be baptized, going down under the cleansing waters, washing away his old and defiled life, being buried by baptism, disappearing, from men's sight as a Gentile, and rising from the water as a new man. He was thus born of water, and this time born, not a Gentile, but a Jew.
The language of our Lord then could scarcely puzzle Nicodemus, but the idea did stagger him that not only Gentiles but Jews must be born again. John had indeed required the same preparation for entrance to the kingdom; but the Pharisees had not listened to John, and were offended precisely on the ground of his baptism. But now Jesus presses upon Nicodemus the very same truth, that as the Gentile had to be naturalized and born again that he might rank as a child of Abraham, and enjoy the external privileges of the Jew, so must the Jew himself be born again if he is to rank as a child of God and to belong to the kingdom of God. He must submit to the double baptism of water and of the Spirit--of water for the pardon and cleansing of past sin and defilement, of the Spirit for the inspiration of a new and holy life.
Our Lord here speaks of the second birth as completed by two agencies, water and the Spirit. To make the one of these merely the symbol of the other is to miss His meaning. The Baptist baptized with water for the remission of sins, but he was always careful to disclaim power to baptize with the Holy Ghost. His baptism with water was of course symbolical; that is to say, the water itself exercised no spiritual influence, but merely represented to the eye what was invisibly done in the heart. But that which it symbolised was not the life-giving influence of the Holy Spirit, but the washing away of sin from the soul. Assurance of pardon John was empowered to give. Those who humbly submitted to his baptism with confession of their sins went from it forgiven and cleansed. But more than that was needed to make them new men--and yet more he could not give. For that which would fill them with new life they must go to a Greater than he, who alone could bestow the Holy Ghost.
These then are the two great incidents of the second birth--the pardon of sin, which is preparatory, and which cuts our connection with the past; the communication of life by the Spirit of God, which fits us for the future. Both of these are represented by Christian baptism because in Christ we have both; but those who were baptized by John's baptism were only _prepared_ for receiving Christ's Spirit by receiving the forgiveness of their sins.
Having thus declared to Nicodemus the necessity of the second birth, He goes on to give the reason of this necessity. Birth by the Spirit is necessary, because that which is born of the flesh is flesh, and the kingdom of God is spiritual. Of course our Lord does not mean by flesh the mere tangible substance of the body; He does not mean that our first and natural birth puts us in possession of nothing but a material frame. By the word "flesh" He signifies the appetites, desires, faculties, which animate and govern the body, as well as the body itself--the whole equipment with which nature furnishes a man for life in this world. This natural birth gives a man entrance into much, and for ever determines much, that has important bearings on his person, character, and destiny. It determines all differences of nationality, of temperament, of sex; apart altogether from any choice of his it is determined whether he shall be a South Sea Islander or a European; an antediluvian living in a cave or an Englishman of the nineteenth century. But the kingdom of God is a spiritual kingdom, into which entrance can be had only by a man's own will and spiritual condition, only by an attachment to God which is no part of a man's natural equipment.