When someone asks me the Christian answer to this question of purpose, the reason for man’s existence, I always take them to the first commandment of Christ. In passing, let us note that there is no reason to think that the first commandment — “You shall love the Lord your God with all your heart and with all your soul and with all your mind” (1)— is merely a first commandment uttered by Jesus. We know it is not so because He quoted it from the last book of Moses, the book of Deuteronomy.
But we can say something more. Surely it is the first commandment because it is the one that expresses the purpose of man and, individually, my purpose. But it is not enough to quote this on its own. Without the answer given by historic Christianity that God is really there, such an answer can only be another cliché to the sincere person seeking truth, just one more twenty first-century “religious answer”; and we cannot blame him if he stops listening. When I hear this first commandment to love the God who is there with everything that I am, it carries with it a total concept of life and of truth. A man can only love a God who exists and who is personal and about whom he has knowledge. So the fact that this God has communicated is also of supreme importance. But this commandment carries something more; it tells me something very fundamental and exciting about myself. there is something electrifying to know about “myself.”
As far as the modern mentality is concerned, it is shattering to be told that there is nothing intrinsically nonsensical in calling upon me to love the God who is there, and that God is of such a nature and that I am of such a nature as to make this a valid proposition. Those who understand what is involved will not dismiss this as “something I have heard since I was little.” To think through the implications is totally exciting. The God who is there is of such a nature that He can be loved, and I am of such a nature that I can love; and thus this first commandment, or basic purpose of man, is the very opposite of a nonsense statement. I know what man is, and I know who I am.
(1) Deuteronomy 6:4-7,Matthew 22:37-40,Mark 12:30-31,Luke 10:27
Thoughts developed and/or taken from the works of Dr. Francis A. Schaeffer, Trilogy – The God Who Is There