In the Recovery Version’s outline of the book of Romans, 5:12 marks a major turning point in Paul’s epistle. Before this point, he has laid out the situation of fallen man and then shown God’s righteousness in justifying those who believe the gospel, based on Christ’s redemption. From this point, there is a turn to the matter of sanctification. The footnote on sanctification in 6:19 is important here:
Sanctification (see note 23 in ch. 1) involves not only a change in position, that is, a separation from a common, worldly position to a position for God, as illustrated in Matt. 23:17, 19 and in 1 Tim. 4:3-5; it involves also a transformation in disposition, that is, a transformation from the natural disposition to a spiritual one by Christ as the life-giving Spirit saturating all the inward parts of our being with God’s nature of holiness, as mentioned in 12:2 and 2 Cor. 3:18.