What is meant by falling from grace?
You probably refer to Gal 5:4. In the first place this epistle to the Galatians is written to the members of the administration of promise, and especially to the Gentile members who had been grafted into the blessings of Israel and the kingdom. To these Paul had preached the gospel of the grace of God, that they might receive all the benefits of the administration of the promise without being circumcised and keeping the law. But there were Judaizers who were convincing some of these Gentiles that they must be circumcised and keep the law. So Paul says to them, For I testify again to every man (Gentile) that is circumcised, that he is a debtor to do the whole law. Christ is become of no effect unto you, whosoever of you (Gentiles) are justified by the law; ye are fallen from grace. So to fall from grace was to leave the grace principle or gospel and go back to circumcision.
