The book of Ecclesiastes explores the question of “Why bother?” Warren Wiersbe provides a good introduction to reading this 12 chapter book of the Bible.
The theme is given in 1:1–3, and might be expressed, “Is life really worth living?” Solomon (the human author) looks at life with its seeming contradictions and mysteries, and he wonders if the “endless toil” of existence is worth it. People toil all their lives, then die, and somebody less worthy inherits their wealth and wastes it. Solomon comes to the conclusion that the best thing to do is to enjoy the blessings of God today, fear God, and keep His Word. Of course, with the added light of the NT we know that “our labor is not in vain in the Lord” (1 Cor. 15:58).
… Keep in mind that Solomon is reasoning about what he sees and knows “under the sun.” If you stop with Ecclesiastes, you will stay in the shadows; you must move on to the full revelation of the New Testament to have the whole counsel of God. Many of the false cults quote isolated verses from this book to prove their strange doctrines. ~ Wiersbe, W. W. 1993. Wiersbe’s expository outlines on the Old Testament. Victor Books: Wheaton, IL