This says it better than I’ve ever heard anyone say it. From Biblical Ethics:
The Bible does not deal with sin as a disease; it does not deal with the outcome of sin, it deals with the disposition of sin itself. The disposition of sin is what our Lord continually faced, and it is this disposition that the Atonement removes. Immediately our evangelism loses sight of this fundamental doctrine of the disposition of sin and deals only with external sins, it leaves itself open to ridicule. We have cheapened the doctrine of sin and made the Atonement a sort of moral “lavatory” in which men can come and wash themselves from sin, and then go and sin again and come back for another washing.
This is the doctrine of the Atonement: “Him who knew no sin” (not sins)—Him who had not the disposition of sin, who refused steadfastly, and to the death on Calvary, to listen to the temptations of the prince of this world, who would not link Himself on with the ruling disposition of humanity, but came to hew a way single-handed through the hard face of sin back to God—“He made to be sin on our behalf; that we might become the righteousness of God in Him” (rv).
The disposition of sin that rules our human nature is not suppressed by the Atonement, not sat on, not cabined and confined, it is removed. Human nature remains unaltered, but the hands and eyes and all our members that were used as the servants of the disposition of sin can be used now as servants of the new disposition (see Romans 6:13). Then comes the glorious necessity of militant holiness. Beware of the teaching that allows you to sink back on your oars and drift; the Bible is full of pulsating, strenuous energy. From the moment a man is readjusted to God then begins the running, being careful that “the sin which doth so easily beset us”does not clog our feet.
I believe that God so radically, so gloriously, and so comprehensively copes with sin in the Atonement that He is more than master of it, and that a practical experience of this can take place in the life of anyone who will enter into identification with what Jesus Christ did on the Cross. What is the good of saying, “I believe in Jesus Christ as the Saviour of the world” if you cannot answer the blunt question, “What has He saved you from?” The test is not in theories and theologies, but in practical flesh and blood experience. Jesus Christ is our Saviour because He saves us from sin, radically altering the ruling disposition. Anyone who has been in contact with the Lord when He alters the ruling disposition knows it, and so do others. But there is a painful, tremendous repentance first. The whole teaching of the Bible on the human side is based on repentance. The only repentant man is the holy man, and the only holy man is the one who has been made so by the marvel of the Atonement. And here comes the wonder—let the blunders of lives be what they may, let hereditary tendencies be what they like, let wrongs and evils crowd as they will, through the Atonement there is perfect readjustment to God, perfect forgiveness, and the gift of a totally new disposition which will manifest itself in the physical life just as the old disposition did (see Romans 6:19). Jesus Christ comes as the last Adam to take away the abnormal thing (which we call natural), the disposition of my right to myself, and He gives us a new disposition, viz., His own heredity of unsullied holiness, Holy Spirit.