John Darby’s Synopsis
 Note here a very important principle, that there are positive advantages of position, where there is no intrinsic change. Compare chapter 11:17, and 1 Corinthians 10.
 Chapter 3:21 reverts in fact to chapter 1:17; what comes between is the demonstration of the ground of chapter 1:18, which made the righteousness of verse 17 imperatively necessary.
 Remark here how, God being revealed, sin is measured by the glory of God. We are so used to read this that we overlook its force. How strange to say, "and come short of the glory of God!" Man might say, Why, of course we have; but, morally speaking, this has been revealed, and if one cannot stand before it, according to it, we cannot subsist before God at all. Of course it is not of His essential glory-all creatures are short of that, of course-but of that which was fitting for, according to, could stand in, His presence. If we cannot stand there, fitly "walk in the light as God is in the light," we cannot be with God at all. There is no veil now.
 To shew how complete is this instruction of Paul's, I give here a summary of its elements. In itself it is the righteousness of God, without law, the law and the prophets bearing witness to it: as to its application, the righteousness of God by faith in Christ Jesus unto all, and upon all them that believe. Christ is proposed as the propitiatory by faith in His blood, to shew forth this righteousness by the remission of past sins (of the Abrahams, etc.) according to the forbearance of God; but to shew it forth in the present time, in order that He may be just, and justify those who believe in Jesus.
 See here again how God is brought out in Himself. Compare Matthew 15:19-28.
 The law is the perfect rule of right and wrong for every child of Adam in itself, though only given to the Jews. But it was not arbitrary. It took up all the relationships in which men stood, gave a perfect rule as to them, and the sanction of God's authority to them, with a penal sanction. But now we have something much higher, not what man ought to be, but God Himself glorified.
 Hence those who put Christians under law do not maintain its authority; for they hold them exempt from its curse, though they break it.