What does Galatians 5:4 mean?
Paul has said repeatedly that choosing between following the law, as opposed to trusting in Christ, as a means to be accepted by God is a choice between slavery and freedom. He has urged the Galatian Christians not to be talked into following the law and thus make themselves slaves to the law (Galatians 4:1–7).Some might be tempted to think they could do both: "Who knows if faith alone, or faith-plus works is right? Do I trust Paul, or the Judaizers? I'll just do it all to make sure I'm covered. I don't want to risk not being accepted by God, after all."
However, Paul is showing his readers that acceptance by God is exactly what they risk by trying to do both. Someone who adds works to faith in Christ "just in case" is not truly trusting in Christ, at all. Now Paul puts it in even harsher terms: That person is "severed" or alienated from Christ. Someone who is trying to be justified—"made right with God"—by following the law has missed out on the grace of God.
It's important to understand that the description given here—"fallen away from grace" in some translations—does not mean this person has lost their salvation. Rather, Paul's suggestion is that such a person had not been trusting in Christ, at all. Grace comes through faith in Christ and by no other means. To seek salvation apart from Christ is to fall away from the opportunity for grace.