Not Christianity at all

My denomination experienced the conflict between "modernism" and "fundamentalism" in the early 20^th century. My grandfather, I think, was among the "modernists." Unlike many Protestant denominations the conflict didn't result in a split, but it did result in many prospective pastors choosing to attend a seminary other than ours.

I identify with Machen's argument. From the Introduction to J. Gresham Machen’s Christianity and Liberalism:

...[T]he great redemptive religion which has always been known as Christianity is battling against a totally diverse type of religious belief, which is only the more destructive of the Christian faith because it makes use of traditional Christian terminology. This modern non-redemptive religion is called "modernism" or "liberalism." Both names are unsatisfactory; the latter, in particular, is question-begging. The movement designated as "liberalism" is regarded as "liberal" only by its friends; to its opponents it seems to involve a narrow ignoring of many relevant facts. And indeed the movement is so various in its manifestations that one may almost despair of finding any common name which will apply to all its forms. But manifold as are the forms in which the movement appears, the root of the movement is one; the many varieties of modern liberal religion are rooted in naturalism—that is, in the denial of any entrance of the creative power of God (as distinguished from the ordinary course of nature) in connection with the origin of Christianity. The word "naturalism" is here used in a sense somewhat different from its philosophical meaning. In this non-philosophical sense it describes with fair accuracy the real root of what is called, by what may turn out to be a degradation of an originally noble word, "liberal" religion. ....

What is the relation between Christianity and modern culture; may Christianity be maintained in a scientific age?

It is this problem which modern liberalism attempts to solve. Admitting that scientific objections may arise against the particularities of the Christian religion—against the Christian doctrines of the person of Christ, and of redemption through His death and resurrection—the liberal theologian seeks to rescue certain of the general principles of religion, of which these particularities are thought to be mere temporary symbols, and these general principles he regards as constituting "the essence of Christianity." ....

...[I]t may appear that what the liberal theologian has retained after abandoning to the enemy one Christian doctrine after another is not Christianity at all, but a religion which is so entirely different from Christianity as to belong in a distinct category. It may appear further that the fears of the modern man as to Christianity were entirely ungrounded, and that in abandoning the embattled walls of the city of God he has fled in needless panic into the open plains of a vague natural religion only to fall an easy victim to the enemy who ever lies in ambush there. ....

...[O]ur principal concern just now is to show that the liberal attempt at reconciling Christianity with modern science has really 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. In trying to remove from Christianity everything that could possibly be objected to in the name of science, in trying to bribe off the enemy by those concessions which the enemy most desires, the apologist has really abandoned what he started out to defend. Here as in many other departments of life it appears that the things that are sometimes thought to be hardest to defend are also the things that are most worth defending. ....

In setting forth the current liberalism, now almost dominant in the Church, over against Christianity, we are animated, therefore, by no merely negative or polemic purpose; on the contrary, by showing what Christianity is not we hope to be able to show what Christianity is, in order that men may be led to turn from the weak and beggarly elements and have recourse again to the grace of God.

Christianity and Liberalism is now in the public domain, and can be downloaded as a pdf here. There is also a new edition with a foreward by Carl Trueman that can be ordered at Amazon.