Martin Luther, commenting on Galatians 5:4, wrote:
It must be noted and pointed out carefully that Paul declares the desire to be justified through the Law to be nothing else than being separated from Christ and being made completely useless by Him. What can be said against the Law that is more powerful, or what can be set in opposition to this thunderbolt? Therefore it is impossible for Christy and the Law to dwell in the heart at the same time. Either the Law or Christ has to yield. But if you are of the opinion that Christ and trust in the Law can dwell together in the heart, then you should know for sure that not Christ but the devil is dwelling in your heart under the mask of Christ, and that he is the one who is accusing you, terrifying you, and demanding the Law and your works as the condition of righteousness. For, as I said a little earlier, the genuine Christ does not chide you for your sins; nor does He command you to trust in your good works. And genuine knowledge of Christ, or faith, does not discuss whether you have done good works to obtain righteousness or evil works to obtain damnation; but it simply declares: “If you have done good works, you are not justified on their account; and if you have done evil works, you are not damned on their account.” I am not taking any of their glory away from good works; nor am I praising evil works. But I am saying that in the issue of justification I must see how I am to keep Christ, lest He become useless to me, in opposition to my evil works and without my good works. If I feel this way about Christ, I grasp the genuine Christ; but if I think that He demands the Law and works of me as a condition for righteousness, then He has become of no advantage to me, and I am severed from Him.
Luther, Martin Luther’s Works, volume 27: Lectures on Galatians 17