Here are some good quotes from John Gresham Machen's book Christianity and Liberalism (1923), written in the wake of the Fundamentalist/Modernist controversy of the late 19th/early 20th century. Just FYI, the Modernist/Liberal position (very much alive today) denies cardinal Christian doctrines like the Inspiration of Scripture, the deity of Christ, the sinfulness of Man, and the Gospel en toto.
... The consiousness of sin was formerly the starting-point of all preaching; but today it is gone. Characteristic of the modern age, above all else, is a supreme confidence in human goodness; the religious literature of the day is redolent of that confidence. Get beneath the rough exterior of men, we are told, and we shall discover enough self-sacrifice to found upon it the hope of society; the world's evil, it is said, can be overcome with the world's good; no help is needed from outside the world. (p. 64)
... The fundamental fault of the modern Church is that she is busily engaged in an absolutely impossible task — she is busily engaged in calling the righteous to repentance. Modern preachers are trying to bring men into the Church without requiring them to relinguish their pride; they are trying to help men avoid the conviction of sin. The preacher gets up into the pulpit, opens the Bible, and addresses the congregation somewhat as follows: "You people are very good," he says; "you respond to every appeal that looks toward the welfare of the community. Now we have in the Bible — especially in the life of Jesus — something so good that we believe it is good enough even for you good people." Such is modern preaching. It is heard every Sunday in thousands of pulpits. But it is entirely futile. Even our Lord did not call the righteous to repentance, and probably we shall be no more successful than He. (p. 68)
... For if one thing is plain it is that Christianity refuses to be regarded as a mere means to a higher end. Our Lord made that perfectly clear when He said: "If any man come to me, and hate not his father and mother ... he cannot be my disciple" (Luke xiv. 26). Whatever else those stupendous words may mean, they certinaly mean that the relationship to Christ takes precedence of all other relationships, even the holiest of relationships like those between husband and wife and parent and child. Those other relationships exist for the sake of Christianity and not Christianity for the sake of them. Christianity will indeed accomplish many useful things in this world, but if it is accepted in order to accomplish those useful things it is not Christianity. Christianity will combat Bolshevism [Marxism/Communism]; but if it is accepted in order to combat Bolshevism, it is not Christianity: Christianity will produce a unified nation, in a slow but satisfactory way: but if it is accepted in order to produce a unified nation, it is not Christianity: Christianity will produce a healthy community; but if it is accepted in order to produce a healthy community, it is not Christianity: Christianity will promote international peace; but if it accepted in order to promote international peace, it is not Christianity. Our Lord said: "Seek ye first the Kingdom of God and His righteousness, and all these things shall be added unto you." But if you seek first the Kingdom of God and His righteous in order that all those things may be added unto you, you will miss both those other things and the Kingdom of God as well. (p. 151-152)
[J. Gresham Machen (1923), Christianity and Liberalism, Eerdmans, Grand Rapids, MI, USA. Bold added]
As it can be seen, such words are still relevant to us nearly one century on. Human nature hasn't changed, and these words are perhaps even more pertinent to us today than they are then. Machen would be spinning in his grave just knowing the state of Evangelicalism today; not to mention the state of the Orthodox Presbyterian denomination which he helped founded (Federal Vision anyone?)