Having been loosed from the law, we did not receive freedom to act lawlessly. Rather, we entered new obligations. We became bound to live a new life according to the commandments of the Gospel, "so that we may serve God in newness of life" (cf. Rom 7:6).
The Apostle's purpose is not to prove the passing away of the law. He takes this truth as already proved and only draws from it the conclusion he needs. He does this by comparing obligation to the law with a wife's obligations to her husband.
As long as the husband lives, the wife is obliged to live with him. When the husband dies, she is free to marry another and live with him. Yet having married another, she is bound by obligations to the new husband equal to the former ones.
The same now holds for believers. They have died to the law, and the law has died to them. All obligations between them have ceased. Yet, having been freed from the law, they give themselves to another, to the Lord Jesus Christ risen from the dead.
Therefore they are obliged to live for Him alone, in His Spirit and in His will. This is the same truth as in the preceding chapter about the obligations of faith: "Consider yourselves dead to sin and alive to God in Christ Jesus our Lord" (cf. Rom 6:11).
Here law stands in place of sin because, for the Apostle, to live under the law is to live in the flesh. It is to know the law's demands without having the power to fulfill them. This is the same as living in sin. He immediately turns to this in this chapter.
The words "brethren" and "for I speak to those who know the law" are pleasant words for those to whom he writes. Yet besides friendliness, they also contain a hidden hint. They cannot refuse to agree with the conclusion that the Apostle is about to propose.
For one who is called knowledgeable about some proposition, and who has accepted this title, will be ashamed not to agree with the direct conclusion drawn from it.
"The law has authority" means it rules, reigns, and possesses binding force over a man. "He did not say, 'over a husband or wife,' but, 'over a man,' since this name belongs to both" (Chrysostom).
"As long as he lives." Who lives, the man or the law? This is not evident from these words. In the following discourse both thoughts are expressed: that the law has died, and that man has died to the law.
Consequently, here one may understand both: as long as the law lives, or as long as the man lives. There is reason to suppose that the Apostle intended to draw a twofold parallel with a twofold conclusion. Whether the law has died or the man has died, their mutual obligations have ceased.
Yet he stopped at one side because from this he reached more closely and quickly the conclusion he needed: "that you may belong to another."
Chrysostom says: "Although he seems to speak of one thing, he nevertheless brings two arguments in confirmation of what was said. The first argument is that, after her husband's death, a wife is not subject to the law of marriage, and she is not forbidden to become another man's wife. The second argument is that, in the present case, not only the husband but also the wife has died, and therefore she enjoys a twofold freedom. If she was freed from authority by the husband's death, she became incomparably freer when she herself was also found to have died. If one circumstance frees her from authority, much more is she free when both circumstances come together."
For Chrysostom's words to be clearer, one must keep in mind that the husband here is called the law, and the wife is the believers. The husband, the law, has died, because with the coming of Christ the Lord it ceased to be what it had been.
The wife, the believers, died when she was buried with the Lord through baptism into death. Thus she became doubly free from the law. There, because the husband was no more. Here, because she herself died.
Yet in dying she drew forth a new life, different from the former one. Therefore, being loosed from former obligations, she freely entered new ones, "that she might belong to another."