...there is no question (could there ever be) that Christians are obligated to serve God. Nor is there (for Paul) any question that believers, as dwellers in God's world, are subject to precisely the same universal obligations of truth, goodness, and love that are spelled out in the moral demands of the Mosaic law. Indeed, when they live as they ought and as they are enabled by the divine spirit that indwells them, their conduct will prove unexceptionable by the standards of the law. They will, in effect, have "fulfilled" the law. Paul's point is rather that believers do not encounter these obligations as law.
"Law," in this Pauline usage, stands not simply for the concrete commands and prohibitions found in Torah, but also for the mode in which these obligations encounter rebellious humanity "in the flesh": as commands that are externally imposed (their inscription on tablets of stone is in marked contrast with demands recognised and endorsed within human hearts) upon a will bent on its self-assertion. The Mosaic law in all of its parts - moral as well as ritual commandments, sanctions as well as demands - was intended for a a favoured people who are nonetheless representative of humanity "in the flesh". Among them it could only exacerbate - while it defined and condemned - humanity's rebellion. For a humanity being prepared for restoration to its intended place in God's creation, for a humanity (as Paul puts it) that has yet to "come of age," God provided a fitting and graphic reminder in his covenant with Israel that he is good, that human beings have been made to enjoy fellowship with him, and that that fellowship requires their own submission to the good. Inevitably, the latter requirement could only encounter Adamic humanity as law.
But law (in this sense) is a matter of the past for a humanity that has "come of age." Its ceremonial aspects were never intended for any but Jews. But even its moral demands now have a different character. To be sure, murder, adultery, and theft are as wrong for Christians as they ever were for Israel "under the law." Moreover, so long as Christians are subject to the weakness and temptations of life in a sin-scarred world, they will need guidance (or, at the least, reminders) about which kinds of behaviour are appropriate and which kinds are inappropriate and wrong for them to show as the redeemed people of God. We may go further. There is, in Paul's understanding, a continuing place for figures of authority in the church to provide such guidance and, if necessary, to insist upon its obligatory nature. Paul himself does not hesitate to advise, to remind, to command. But even when he commands, he insists that he is merely spelling out what is implicit in his Christian readers' own faith and experience of God. Appropriate behaviour for believers is, for Paul, the natural expression of their trust in God and their experience of his indwelling spirit. They have "crucified the flesh;" no longer, then, can God's will confront them as an arbitrary, vexing and provocative law.
Stephen Westerholm, Preface to the study of Paul, Eerdmans 1997, p.92f
