In reality Tyndale is trying to express an obstinate fact which meets us long before we venture into the realm of theology; the fact that morality or duty (what he calls ‘the Law’) never yet made a man happy in himself or dear to others. It is shocking, but it is undeniable. We do not wish either to be, or to live among, people who are clean or honest or kind as a matter of duty: we want to be, and associate with, people who like being clean and honest and kind. The mere suspicion that what seemed an act of spontaneous friendliness or generosity was really done as a duty subtly poisons it. In philosophical language, the ethical category is self-destructive; morality is healthy only when it is trying to abolish itself. In theological language, no man can be saved by works. The whole purpose of the “Gospel,” for Tyndale, is to deliver us from morality. Thus, paradoxically, the “Puritan” of modern imagination—the cold, gloomy heart, doing as duty what happier and richer souls do without thinking of it—is precisely the enemy which historical Protestantism arose and smote.
C.S. Lewis, English Literature in the Sixteenth Century, p. 187.