4Yet because of false brothers secretly brought in—who slipped in to spy out our freedom that we have in Christ Jesus, so that they might bring us into slavery— 5 to them we did not yield in submission even for a moment, so that the truth of the gospel might be preserved for you.
The Holy Bible: English Standard Version. (2016). (Ga 2:4–5). Wheaton, IL: Crossway Bibles.
The false apostles preached the Gospel, but they did so with this condition attached to it. The scholastics do the same thing in our day. They say that we must believe in Christ and that faith is the foundation of salvation, but they say that this faith does not justify unless it is “formed by love.” This is not the truth of the Gospel; it is falsehood and pretense. The true Gospel, however, is this: Works or love are not the ornament or perfection of faith; but faith itself is a gift of God, a work of God in our hearts, which justifies us because it takes hold of Christ as the Savior. Human reason has the Law as its object. It says to itself: “This I have done; this I have not done.” It does not look at its love and say: “What have I done? Where have I sinned? What have I deserved?” But it says: “What has Christ done? What has He deserved?” And here the truth of the Gospel gives you the answer: “He has redeemed you from sin, from the devil, and from eternal death.” Therefore faith acknowledges that in this one Person, Jesus Christ, it has the forgiveness of sins and eternal life. Whoever diverts his gaze from this object does not have true faith; he has a phantasy and a vain opinion. He looks away from the promise and at the Law, which terrifies him and drives him to despair.
Luther, M. (1999). Luther’s works, vol. 26: Lectures on Galatians, 1535, Chapters 1-4. (J. J. Pelikan, H. C. Oswald, & H. T. Lehmann, Eds.) (Vol. 26, p. 88). Saint Louis: Concordia Publishing House.