But underlying much of the conscious rejection of spiritual discipline is the fear of legalism… But nothing could be farther from the truth if you understand what discipline and legalism are. The difference is one of motivation: legalism is self-centered; discipline is God-centered. The legalistic heart says, “I will do this thing to gain merit with God.” The disciplined heart says, “I will do this thing because I love God and want to please Him.” There is an infinite difference between the motivation of legalism and discipline! (Paul) knew this implicitly and fought the legalists bare-knuckled all the way across Asia Minor, never giving an inch. And now he shouts to us, “Train (discipline) yourself to be godly”! If we confuse legalism and discipline, we do so to our soul’s peril.
Kent Hughes