"So the error of the Judaizers is a very modern error indeed, as well as a very ancient error. It is found in the modern Church wherever men seek salvation by "surrender" instead of by faith, or by their own character instead of by the imputed righteousness of Christ, or by "making Christ master in the life" instead of by trusting in His redeeming blood. In particular, it is found wherever men say "the real essentials" of Christianity are love, justice, mercy and other virtues, as contrasted with the great doctrines of God's Word. These are all just different ways of exalting the merit of man over against the Cross of Christ, they are all of them attacks upon the very heart and core of the Christian religion. And against all of them the mighty polemic of this Epistle to the Galatians is turned."
-J. Gresham Machen (Commentary on Galatians)
[Hat Tip: Nick Batzig]