30 But what does the Scripture say? “Cast out the bondwoman and her son, for the son of the bondwoman shall not be an heir with the son of the free woman.” 31 So then, brethren, we are not children of a bondwoman, but of the free woman (Galatians 4).
A “bondwoman” and a “free woman” cannot live together in the same household. One or the other must be “cast out” if there is to be any harmony there. For the believer it is the bondwoman who must leave, for she is the one who would bear offspring who would be slaves to the Law along with her.
This is all to say that you cannot have salvation by grace and works both at the same time, that is, you cannot be saved by grace and by works—it is one or the other. The true Christian is saved by grace through faith in the One who redeemed him through His blood. We are saved by His work—not ours, and thus have His righteousness, and not our own.
Lord, thank You for making grace our mother instead of works. Help us This Day to walk as children of grace. Amen.