“For you, brethren, have been called to liberty; only do not use liberty as an opportunity for the flesh, but through love serve one another” (Galatians 5:13).
Having clearly established that this discussion is a contrast between the son of the bondwoman and the son of the freewoman—between those who lived under the law of Moses and those who are living under the law of Christ—Paul speaks once again of the liberty in Christ.
This liberty, then, means freedom from the constraints of the law of Moses as well as freedom from the burden of past sins—in Christ, all who have obeyed Christ have been freely forgiven, something the Old Law could not provide.
The message is that the Galatians are not free to use this liberty as an excuse to indulge in the sins of the flesh—they are not free to do anything they want to do. Rather, they are to practice the law of love in caring for one another. Even those living under a law of liberty must submit to the conditions established within that law.
In establishing this principle contained in the law of Christ, Paul reinforces other passages and makes clear for all living in the Christian Age the idea that liberty is not a license to sin but a structure to be honored.