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.
As soon as we clearly see what the kingdom of God is, we see also that by nature we do not belong to it. The kingdom of God so far as man is concerned is a state of willing subjection to Him—a state in which we are in our right relation to Him. All irrational creatures obey God and do His will: the sun runs his course with an exactness and punctuality we cannot rival; the grace and strength of many of the lower animals, their marvellous instincts and aptitudes, are so superior to anything in ourselves that we cannot even comprehend them. But what we have as our speciality is to render to God a willing service; to understand His purposes and enter sympathetically into them. The lower creatures obey a law impressed upon their nature; they cannot sin; their performance of God’s will is a tribute to the power which made them so skilfully, but it lacks all conscious recognition of His worthiness to be served and all knowledge of His object in creation. It is God serving Himself: He made them so, and therefore they do His will. So it is with men who merely obey their nature: they may do kindly, noble, heroic actions, but they lack all reference to God; and however excellent these actions are, they give no guarantee that the men who do them would sympathize with God in all things, and do His will gladly.