I admire the late Loraine Boettner for many things: he was a clear-thinking theologian and teacher, an author of many helpful books (including books on the Reformed faith and post-millennialism), he was a devoted churchman and member of the Orthodox Presbyterian Church, and he worked for the Library of Congress. This excerpt from his helpful short book The Atonement is worth quoting at length.
“Thus the death of Christ emerges as the central truth in the Christian doctrine of redemption. It is the link which holds together all of the other distinctive doctrines. The mark of His blood is upon them and signifies their ownership, as the scarlet thread running through every cord and rope of the British navy signifies that it is the property of the crown. It hardly seems possible that, with this central truth written so plainly and so repeatedly across the pages of Scripture, any honest or serious minded persons could arise, as do the Unitarians and Modernists, and declare that the essence of Christianity consists in our following the example of Christ in lives of social service, or that the chief purpose of the Church is to build a new social order in this world. It is very evident, of course, that in our daily lives we are to follow the example of Christ as closely as possible. And in due course of time a new social order, based on justice and improved living conditions, will gradually arise as Christian principles are applied first to the lives of individuals and through them to the life of the community. In many limited social groups we already see the effects of this uplifting process. But Christ’s expiatory death is no more an object for our imitation than is the creation of the world. For in His death he took man’s place and rendered to divine justice a satisfaction which man himself was utterly unable to render. That Christianity is not primarily a social movement, but a redemptive religion, setting forth a way of escape from sin, is as plain as it is possible for words to make it.”
-Lorraine Boettner in The Atonement (1941), from chapter two