Man, made in the image of God, has a purpose - to be in relationship to God, who is there. Man forgets his purpose and thus he forgets who he is and what life means.
If man has been kicked up out of that which is only impersonal by chance , then those things that make him man-hope of purpose and significance, love, motions of morality and rationality, beauty and verbal communication-are ultimately unfulfillable and thus meaningless.
And the purpose of our creation, in which all our subsidiary purposes fit, is to be in a personal relationship to God, in communion with him, in love, by choice, the creature before the Creator.