In the past few posts we have drawn upon the work of James S. Stewart. If you are like me you have never heard of this individual before. Stewart is a Scottish preacher and taught at the University of Edinburgh. He served as the Chaplain to the Queen in Scotland. In addition, Preaching Magazine in 1999 proclaimed Steward the best preacher of the 20th century. So maybe we should pay attention when he speaks to the essential message of Christianity as he does in his book A Faith to Proclaim.
In this book Stewart states that the problem for Christianity today is not secularism but a reduced Christianity.  What is a reduced Christianity? To me Evgeny Barabanov explains best what Stewart means.
It turned out to be too hard to accept all the complexities and antinomies [a contradiction or inconsistency between two apparently reasonable principles or laws] of the Gospel. And that greatest of all temptations began to rear its head—that of “simplifying” Christianity, of reducing it from being a teaching about the new life to a mere caring for the salvation of one’s own soul.
These two aspects of the Christian attitude to the world, active participation in its transformation and renunciation of its temptations, turned out to be extremely difficult to reconcile. Heavenward aspirations often went hand in hand with execration [a detesting, loathing] of the earth. Too often the ideal of salvation was built on a foundation of inflexible renunciation of this world. Thus salvation itself was understood as an escape from the material world into a world of pure spirituality. This gave rise to contempt for the flesh, the belittling of man’s creative nature and, as a necessary consequence, a special religious individualism.
It seems at times that we Christians deliberately do not wish to understand our historical failure or to admit our historical sins. We shift the blame onto anyone we can find—the state, atheism, secularization—but ourselves always remain only innocent victims. . . The world, of course, has abandoned the Church, since the traditional groove reserved for creativity turned out to be too restricted for man. . . Today it is not the Church but the world which is creating a new civilization, and it is solving the problems with which it is faced on the basis of its own understanding of existence. . . Dragging along behind the world, the Church has been left to adopt principles which at first were alien to it, but which by now have become firmly established in spite of it. 
Maintaining that salvation is only by belief in Jesus and his death for our sins has its consequences. It reduces Christianity to a concern about the salvation of our soul and ignores the new life that God has planned for us. And because it only addresses our lives after we die and totally fails to adequately address the problems everyone in the world faces, the world ignores our message. That is sad because the gospel does have the power to transform if we would just put it into practice.
 James S. Stewart, A Faith to Proclaim, Vancouver, British Columbia: Regent College Publishing, 1953, p. 31.
 Evgeny Barabanov, “Schism Between the Church and World”, Alexander Solzhenitsyn, ed., From Under the Rubble, New York: Bantam Books, 1975, pp. 180-186.