romans 8:3 For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh: - Free Bible Online

      3, 4. For what the law could not do, &c.--a difficult and much controverted verse. But it is clearly, we think, the law's inability to free us from the dominion of sin that the apostle has in view; as has partly appeared already (see on Ro 8:2), and will more fully appear presently. The law could irritate our sinful nature into more virulent action, as we have seen in Ro 7:5, but it could not secure its own fulfilment. How that is accomplished comes now to be shown.
      in that it was weak through the flesh--that is, having to address itself to us through a corrupt nature, too strong to be influenced by mere commands and threatenings.
      God, &c.--The sentence is somewhat imperfect in its structure, which occasions a certain obscurity. The meaning is, that whereas the law was powerless to secure its own fulfilment for the reason given, God took the method now to be described for attaining that end.
      sending--"having sent"
      his own Son--This and similar expressions plainly imply that Christ was God's "OWN SON" before He was sent--that is, in His own proper Person, and independently of His mission and appearance in the flesh (see on Ro 8:32 and Ga 4:4); and if so, He not only has the very nature of God, even as a son of his father, but is essentially of the Father, though in a sense too mysterious for any language of ours properly to define (see on the first through fourth chapters). And this peculiar relationship is put forward here to enhance the greatness and define the nature of the relief provided, as coming from beyond the precincts of sinful humanity altogether, yea, immediately from the Godhead itself.
      in the likeness of sinful flesh--literally, "of the flesh of sin"; a very remarkable and pregnant expression. He was made in the reality of our flesh, but only in the likeness of its sinful condition. He took our nature as it is in us, compassed with infirmities, with nothing to distinguish Him as man from sinful men, save that He was without sin. Nor does this mean that He took our nature with all its properties save one; for sin is no property of humanity at all, but only the disordered state of our souls, as the fallen family of Adam; a disorder affecting, indeed, and overspreading our entire nature, but still purely our own.
      and for sin--literally, "and about sin"; that is, "on the business of sin." The expression is purposely a general one, because the design was not to speak of Christ's mission to atone for sin, but in virtue of that atonement to destroy its dominion and extirpate it altogether from believers. We think it wrong, therefore, to render the words (as in the Margin) "by a sacrifice for sin" (suggested by the language of the Septuagint and approved by CALVIN, &c.); for this sense is too definite, and makes the idea of expiation more prominent than it is.
      condemned sin--"condemned it to lose its power over men" [BEZA, BENGEL, FRASER, MEYER, THOLUCK, PHILIPPI, ALFORD]. In this glorious sense our Lord says of His approaching death (Joh 12:31), "Now is the judgment of this world; now shall the prince of this world be cast out," and again (see on Joh 16:11), "When He (the Spirit) shall come, He shall convince the world of . . . judgment, because the prince of this world is judged," that is, condemned to let go his hold of men, who, through the Cross, shall be emancipated into the liberty and power to be holy.
      in the flesh--that is, in human nature, henceforth set free from the grasp of sin.

JFB.