Ecclesiastes is the strangest book in the Bible or, at any rate, the book whose presence in the sacred canons of Judaism and of Christianity is most inexplicable. The Song of Songs with its frankly erotic tone may seem equally out of place in company with the Law and the Prophets, and has seemed so to not a few Jews and Christians in ancient and modern times. …it denies some of the things on which the other writers lay the greatest stress – notably that God has revealed himself and his will to man, through his chosen people, Israel. In Ecclesiastes, God is not only unknown to man through revelation; he is unknowable through reason, the only means by which the author believes knowledge is attainable. Such a God is not Yahweh, the covenant God of Israel. He is rather the mysterious, inscrutable Being whose existence must be presupposed as that which determines the life and fate of man, in a world man cannot change, and where all his effort and values are rendered meaningless.
Thus, in place of a religion of faith and hope and obedience, this writer expresses a mood of disillusionment and proffers a philosophy of resignation.
R.B.Y. Scott, Proverbs and Ecclesiastes (Garden City, NY: Doubleday & Company, 1965), 191.