“You have been severed from Christ, you who are seeking to be justified by law; you have fallen from grace.” (Galatians 5:4)
For many years Galatians 5:4 has been quoted as a “proof text” by those who believe that a Christian can lose their salvation. But this verse makes SO much more sense when you see it in the context of this section, and the whole message of Galatians.

The Boof of Galatians as a whole is a warning against trusting in legalism, instead of God’s grace in Christ. And the expression which opens the verse, “severed from Christ,” is very picturesque, following :3, which referred to circumcision. Paul asserts in a very graphic way, that just as the foreskin of a male is cut off in that Jewish ritual, so a person is “cut off” from the grace of Christ when he trusts legalistic works instead of grace. In other words, Paul is saying you can’t be a Christian (who knows he is saved by grace alone through faith alone in Christ alone) and rely on legalistic practices too. Legalism separates you from grace.

Thus Galatians 5:4 is not the “proof text” for how an individual Christian can “lose his salvation” that many think it is. Rather it is indicating that if you choose to trust legalistic works instead of Christ, you have “cut yourself off;” or “fallen” from the realm of grace, and now face the condemnation that inevitably comes to those who try to earn their salvation by human works instead.