Through sin man did not change essentially. He still is the same personal, rational, moral, psychological, material, earthly being. And from a natural point of view he still stands in the same relation to the world about him. Of course, even from a natural point of view he lost much, in fact, most, of his original power and of his natural gifts. He only retained, according to our confessions, a few and small remnants of them. This is especially evident in regard to his knowledge of earthly things. But that does not remove the fact that he still remains man. The influence of sin is of a spiritual and ethical nature. Spiritually and ethically his nature was now put into reverse. His knowledge became darkness and the lie. His righteousness was changed into unrighteousness and iniquity. His holiness became hatred of the living God. Instead of the love of God in his heart, there was now enmity against the Most High. For the minding of the flesh is enmity against God. And out of that heart are the issues of life also in the natural man, as we have seen above. Because his heart became evil, his thinking and willing, his inclinations and deepest recesses of his nature also became evil, and became evil entirely. He became an enemy of God in all his life, in all his thinking and willing and desiring. Also in the natural man there is no conflict from a spiritual, ethical viewpoint. He loves sin with all his heart, and follows it in all his life. He is an enemy of God. He minds and wills and desires sin. He is totally depraved, and stands in enmity against God with his whole being, with heart and soul and strength.
However, the Christian is fundamentally and principally renewed through the work of the Spirit in regeneration. And also this change is not an essential change, but a spiritual and ethical conversion. Also the regenerated man remains man. His nature remains a spiritual, ethical, moral, psychological, material, earthly nature. And he remains in the same relation to the earthly creation as before his regeneration. Nor is he entirely delivered from death and from the operations of death in his members. The suffering of this present time is also his suffering as long as he stands, through the body, in organic relationship with our human race and with the world about him. Nor does he regain the original, natural gifts in all their power and glory. He retains the likeness of sinful flesh. But from a spiritual, ethical viewpoint he underwent a radical change. He has gone from death into life, from darkness into light, from unrighteousness into righteousness, from the corruption of his nature into holiness. And also this change is presented in Scripture as a radical change of the heart. The proper life-center of this change is found in the resurrection and glorification of Christ. Through His Spirit Christ Himself dwells in the heart of the elect sinner, and connects that heart forever with Himself. He is in Christ, and Christ dominates that heart by His grace. He imparts to that heart new life—His own, resurrection life, the life of God—so that the Christian may boast with the apostle, “I live, but not I; Christ lives in me.” And from that heart the lines run, from an ethical, spiritual viewpoint, throughout his whole nature. If anyone is in Christ Jesus, he is a new creature. Old things are passed away; behold, all things are become new. The Christian wills and thinks, desires and longs, hears and sees, tastes and touches, speaks and acts differently from the natural man. He has become partaker of the divine nature. And the motive-power of his whole life is the love of God in Jesus Christ our Lord.
However, that new life of the Christian meets with all kinds of opposition, an opposition which frequently brings him into captivity to the law of sin which is in his members. In the first place—to start with the periphery of things—there is the old world, to which he belongs from a natural point of view, in which he must live, and on which from a natural viewpoint he is dependent for his whole existence. And in that old world are the old sinful forms of life, the lust of the flesh, the lust of the eyes, and the pride of life. These sinful forms of life he meets everywhere. In the world is the language which he learns, is the garment which he wears, is the book he reads. With the sinful forms of that world he is in contact in commerce and industry, in state and society, in factory and office, on the street and in the home. These forms are apt to lead him astray and take him into captivity under the law of sin, so that he does not do that which he wills.
In the second place, we must remember that according to his nature, his old nature, he also is of that world. By nature he is born of a sinful race, and therefore receives a nature in which for centuries the principle of sin, the principle of enmity against God, has been operating. The Christian does not stand individualistically by himself. He is organically one with our race. The human nature which he receives through his parents is centuries old. And in that human nature, in body and soul, in mind and will, deep ruts have been dug through the operation of sin. Even as the world in which the Christian lives and moves is not yet the new creation, in which righteousness dwells, so also his body is not yet the body of the resurrection, the spiritual body. And his nature is not yet the glorified human nature. And these operations of sin, the ruts of sin, the Scripture calls “the motions of sin in our members,” and “the flesh,” and “the body of this death.” And although this must not be understood in such a way that sin is really material and physical, it nevertheless is clear from all these expressions that especially the body, the psychical body, has been long an instrument of sin, and that it adapts itself very easily to the sinful forms of life in the world, and thus takes us into captivity under the law of sin which is in our members. With the Christian that is regenerated, evil thoughts and desires do no longer issue from the regenerated heart. That, of course, is impossible. Certainly, he has received a new heart through the grace of our Lord Jesus Christ. But in his nature there still are the operations of sin. And this causes conflict and opposition, so that he is frequently led astray in the direction of unrighteousness.
Thus we can somewhat understand that the same person can appear in this world as two egos. The one and the same person, the one subject in him of all his actions, of all his thinking and willing, seems to become two egos from a spiritual, ethical point of view. As far as his person is the subject and knows himself responsible for all the acts and operations of sin in his nature, he is brought into captivity under the law of sin which is in his members. He performs that which is evil, and he is a servant of sin. But in as far as the same person is subject of the new operations of the new life that arises from his regenerated heart, he nevertheless hates evil. He hates even the evil which he does, and while he does it; and he loves the good and strives after sanctification of life. And yet these two are not identical, not even before his own consciousness. For even his own consciousness is such that old things have passed away, and that all things have become new, so that he can say: “It is no more I that do it, but sin that dwelleth in me.” The old man of sin and the new man in Christ do not stand on the same level. The old man is his person as it is the subject of the old operations of sin in his nature. And the new man is the same person, but now as it is the subject of the operations of grace and righteousness in the same nature. But they do not stand in the same position or on the same level, even before his own consciousness. He certainly is conscious of the fact that the operations of sin do not arise any more out of his heart. That heart is regenerated; and he certainly does not have two hearts. Even when he sins, he sins differently from the purely natural man. Even when he sins, he is sorry for his sin. Even though sin is not dead in him, yet he certainly is dead to sin. He does that which he hates; but nevertheless, he hates it. Formerly he loved sin; now he has become an enemy against all sin.
Thus it will become clear that the life of sanctification is and must be a continual battle, even unto the day of our death. Sanctification, therefore, certainly does not consist in this, that the Christian gradually becomes more perfect, more regenerated, and that he is gradually delivered from his old nature. For according to the Heidelberg Catechism, the very holiest has but a small beginning of the new obedience. But sanctification does consist in a continual putting off of the old nature, and the continual putting on of the new man, and in a continual battle, therefore, to let the power of grace even from the heart dominate the motions of sin which are in his members to the end of his life upon earth The Christian must fight the good fight of faith against Satan, the flesh, and the world, and that too, to the very end of his life upon earth.