Harrowing words.
"You are severed from Christ, you who would be justified by the law; you have fallen away from grace." (Galatians 5:4)
In this passage, Paul narrows down and hones in on an important part of his audience and now addresses those among the Galatians who have already accepted the principle of winning God’s approval by following the Law. This is made clear by "you who would be." Other modern translations give the impression that Paul is still talking to all the Galatians, but the context does not support this interpretation.
To be put right with God by obeying the Law is literally “to be justified by the law” (compare the expressions used in Gal 2:16 and Galatians 3:11). In this context those of you who would be put right with God may be rendered as “those of you who try to get right with God,” “… put yourselves right with God,” or “… become right with God.”
Those who put their trust in the Law as a means of winning God’s approval have cut themselves off from Christ. The verb here is used by Paul elsewhere in this letter (Galatians 3:17) to mean “nullify” or “make ineffective” (compare also Paul’s use of this verb in Rom 7:2, where it relates to “being freed from a marriage bond”), and so here it would mean to be separated from Christ (NEB “your relation with Christ is completely severed”). That means that they are no longer in Christ, that is, in union and fellowship with him.
Have cut yourselves off from Christ may thus be rendered as “have completely separated yourselves from Christ.” This meaning may be expressed idiomatically in some languages as “have destroyed your bond with Christ,” or “have destroyed what ties you to Christ.”
Furthermore, they are outside God’s grace (literally, “you have fallen away from grace”). Grace here may refer either to God’s or Christ’s grace, but most translators prefer the former interpretation. So here also as in Galatians 1:6, grace includes the components of undeserved love and free gift. To obey the Law in order to win God’s approval is to turn one’s back on God’s gift of sonship. The expression “you have fallen away” should be understood, not in the sense that grace has been taken away from them, but in the sense that they have turned their backs on it. One may also say “you have put yourself in a place where God’s goodness cannot find you,” “… where God cannot be good to you,” or “… show you his goodness.”
Paul’s primary point in this passage, as throughout the letter, is that law and grace cannot be mixed. As a means to salvation they are totally incompatible and mutually exclusive. To mix law with grace is to obliterate grace. For a believer to start living again under the law to merit salvation is, in fact, to reject salvation by grace. Contrary to the teaching of the Judaizers, to add circumcision and other works of the law to what Christ accomplished by grace is not to raise one’s spiritual level but to severely lower it. Legalism does not please God but offends Him. It does not bring a person closer to God but rather drives him away.