J. Gresham Machen's magnum opus, Christianity & Liberalism, is a book that everyone concerned about the demise of American Christianity should read. At first one might not find the title of his book all that striking, but in its day (1923), it had a little more punch. Machen was trying to show that Christianity and liberalism were two separate plans of salvation, two separate faiths--in short, two entirely different religious systems. In his day, it was thought that liberalism was a fresh new approach to Christianity, a way of practicing the faith in the modern context. But in Machen's thinking, however, liberalism had "relinquished everything distinctive of Christianity, so that what remains is in essentials only that same indefinite type of religious aspiration which was in the world before Christianity came upon the scene." Machen set out therefore to bring all the issues out into the open and make clear-cut distinctions between the two faiths: "What that message is can be made clear, as is the case with all definition, only by way of exclusion, by way of contrast." But this approach wasn't always well received: "Presenting an issue sharply is indeed by no means a popular business at the present time....Clear-cut definition of terms in religious matters, bold facing of the logical implications of religious views, is by many persons regarded as an impious proceeding...But with such persons we cannot possibly bring ourselves to agree. Light may seem at times to be an impertinent intruder, but it is always beneficial in the end. The type of religion which rejoices in the pious sound of traditional phrases, regardless of their meanings, or shrinks from "controversial" matters, will never stand amid the shocks of life. In the sphere of religion, as in other spheres, the things about which men are agreed are apt to be the things that are least worth holding; the really important things are the things about which men will fight." Machen was an extremely clear writer! and thinker. His insight with regard to the battle of orthodox Christianity in the liberal context of the 20's is of tremendous relevance for modern Christians of all stripes concerned about the loss of substance, meaning, theology, etc, in the contemporary church. After reading Christianity & Liberalism, you'll definately want to order his other classic, What Is Faith (1925).