Luther's Commentary on the Letter to the Galatians, chapter 5: As he approaches the end of the epistle, Paul argues vigorously and passionately in defense of the doctrine of faith and of Christian liberty against the false apostles, who are its enemies and destroyers. He aims and hurls veritable thunderbolts of words at them to lay them low. At the same time he urges the Galatians to avoid their wicked doctrine as though it were some sort of plague. In the course of his urging he threatens, promises, and tries every device to keep them in the freedom achieved fro them by Christ. Therefore he says:
1. For freedom Christ has set us free; stand fast therefore.
That is: "Be firm!" thus Peter says (1 Peter 5:8-9): "Be sober, be watchful. Your adversary the devil prowls around like a roaring lion, seeking someone to devour. resist him, firm in your faith." "do not be smug," he says, "but be firm. Do not lie down or sleep, but stand." It is as though he were saying: "vigilance and steadiness are necessary if you are to keep the freedom for which Christ has set us free. those who are smug and sleepy are not able to keep it." For Satan violently hates the light of the Gospel, that is, the teaching about grace, freedom, comfort, and life. Therefore as soon as he sees it arise, he immediately strives to obliterate it with all his winds and storms. for this reason Paul urges godly persons not to be drowsy and smug in their behavior but to stand bravely in the battle against Satan, let he take away the freedom achieved from them by Christ.
Every word is emphatic. "Stand fast," he says, "in freedom." In what freedom? Not in the freedom for which the roman emperor has set us free but in the freedom for which Christ has set us free. The Roman Emperor gave--indeed, was forced to give--the Roman pontiff a free city and other lands, as well as certain immunities, privileges, and concessions. This, too, is freedom; but it is a political freedom, according to which the Roman pontiff with all his clergy is free of all public burdens. In addition, there is the freedom of the flesh, which is chiefly prevalent in the world. Those who have this obey neither God nor the laws but do what they please. This is the freedom which the rabble pursues today; so do the fanatical spirits, who want to be free in their opinions and actions, in order that they may teach and do with impunity what they imagine to be right. This is a demonic freedom, by which the devil sets the wicked free to sin against God and men. We are not dealing with this here although it is the most widespread and is the only goal and objective of the entire world. Nor are we dealing with political freedom. No, we are dealing with another kind, which the devil hates and attacks most bitterly.
This is the freedom with which Christ has set us free, not from some human slavery or tyrannical authority but from the eternal wrath of God. Where? In the conscience. This is where our freedom comes to a halt; it goes no further. For Christ has set us free, not for a political freedom or a freedom of the flesh but for a theological or spiritual freedom, that is, to make our conscience free and joyful, unafraid of the wrath to come (Matt. 3:7). This is the most genuine freedom; it is immeasurable. When the other kinds of freedom--political freedom and the freedom of the flesh--are compared with the greatness and the glory of this kind of freedom, they hardly amount to one little drop. For who can express what a great gift it is for someone to be able to declare for certain that God neither is nor ever will be wrathful but will forever be a gracious and merciful Father for the sake of Christ? It is surely a great and incomprehensible freedom to have this supreme Majesty kindly disposed toward us, protecting and helping us, and finally even setting us free physically in such a way that our body, which is sown in perishability, in dishonor, and in weakness, is raised in imperishability, in honor, and in power (1 Cor. 15:42-43). Therefore the freedom by which we are free of the wrath of God forever is greater than heaven and earth and all creation.
From this there follows the other freedom, by which we are made safe and free through Christ from the law, from sin, death, the power of the devil, hell, etc. for just as the wrath of God cannot terrify us--since Christ has set us free from it--so the Law, sin, etc, cannot accuse and condemn us. Even though the Law denounces us and sin terrifies us, they still cannot plunge us into despair. For faith, which is the victor over the world (1 John 5:4), quickly declares: "Those things have nothing to do with me, for Christ has set me free from them."