The true darkness and sadness for modern man who does not believe in the God who is there is that he cannot have any certainty of the relationship of the subject and the object of what he sees, feels, and knows about the reality of his existence.  But the Christian position starts from another set of presuppositions altogether, that there is a reason for a correlation between the subject and the object.  This is the experience of all men.  If it were some mystical, religious thing that somebody offers as a leap completely out of reality and with no way to test it objectively, it would indeed be just one more piece of pie in the sky.  But it does not matter how thoroughly a man in his philosophy holds a concept of unrelatedness and meaningless to life and existence; in reality he lives as though there is a correlation between subject and object (existence, life, cause and effect).   

The fact is that if we are going to live in this world at all, we must live in it acting on a correlation of ourselves and the reality of what we see, feel, and know, even if we have a philosophy that says there is no correlation.  There is no other way to live in this world.  Even the person who holds theoretically the most consistent concept of believing that there is no relationship between our being and existence, lives in this world on the basis of his experience that there is a correlation between being and existence and cause and effect.  He not only lives that way, he has to live that way.  There is no other way to live in this world.  That is the way the world is made.  So just as men love even if they say love does not exist, and all men have moral motions, even though the say moral motions do not exist, so all men act as though there is a correlation between the external and the internal world, even if they have no basis for that correlation.  What we are saying is that the Christian view is exactly in line with the experience of every man.  But no other system except the Judeo-Christian one – that which is given in the Old and New Testaments together – tells us why there is a subject-object correlation.  Everybody does act on it, everybody must act on it, but no other system tells you why there is a correlation between the subject and object.  In other words, all men constantly and consistently act as though Christianity is true.   

No matter what a man says he believes, actually –every moment of his life – he is acting as though Christianity were true, and it is only the Christian system that tells him why he can, must, and does act the way he does.   

Thoughts developed and/or taken from the works of Dr. Francis A. Schaeffer, Trilogy – He Is There and He Is Not Silent