When I speak of liberal Protestants, I have in mind those Protestants who feel free to depart from classical Protestantism (the Protestantism of the Reformers) in order, as they see it, to keep Christianity in step with the best of secular wisdom—a secular wisdom that often includes attacks on Christianity. Over the past 250 years there have been three great attacks on Christianity: deism, agnosticism, and the sexual revolution. And so, beginning with Unitarianism more than 200 years ago, liberal Protestantism has adjusted to these attacks by dropping more and more of traditional Christian doctrine, until today the more advanced liberal Protestants are only barely distinguishable from atheists.