1. Playing the Fool
Then Saul said, “I have sinned. Return, my son David. For I will harm you no more, because my life was precious in your eyes this day. Indeed I have played the fool and erred exceedingly” (1 Sam. 26:21).

2. Saying “There Is No God.”
Ps. 14:1 The fool has said in his heart, "There is no God." Gen. 1:1 In the beginning God created the heavens and the earth. Ps. 19:1 The heavens declare the glory of God; And the firmament shows His handiwork. Ps. 90:1 Lord, You have been our dwelling place in all generations. Before the mountains were brought forth, Or ever You had formed the earth and the world, Even from everlasting to everlasting, You are God. Acts 17:28 for in Him we live and move and have our being, as also some of your own poets have said, “For we are also His offspring.”

3. The fool has said in his heart, “There is no God.”
Rom. 1:18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who suppress the truth in unrighteousness, 19 because what may be known of God is manifest in them, for God has shown it to them. 20 For since the creation of the world His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and Godhead, so that they are without excuse, 21 because, although they knew God, they did not glorify Him as God, nor were thankful, but became futile in their thoughts, and their foolish hearts were darkened. 22 Professing to be wise, they became fools.
To Deny God is to Play the Fool!

4. Living By One’s Own Standard Is Foolish
Prov. 12:15 The way of a fool is right in his own eyes, But he who heeds counsel is wise.
Prov. 28:26 He who trusts in his own heart is a fool, But whoever walks wisely will be delivered.
WHY?
Jer. 10:23 O LORD, I know the way of man is not in himself; It is not in man who walks to direct his own steps.
Isa. 55:8-9 “For My thoughts are not your thoughts, Nor are your ways My ways,” says the LORD. “For as the heavens are higher than the earth, So are My ways higher than your ways, And My thoughts than your thoughts.”

5. Living By One’s Own Standard Is Foolish
Downfall of Israel:
Jud. 21:25 …everyone did what was right in his own eyes.
Naaman’s thought was wrong (1 Kgs. 5:11).
Need to ask:
Rom. 4:3 For what does the Scripture say?
1 Sam. 3:10 Now the LORD came and stood and called as at other times, "Samuel! Samuel!" And Samuel answered, "Speak, for Your servant hears."
Acts 10:33 So I sent to you immediately, and you have done well to come. Now therefore, we are all present before God, to hear all the things commanded you by God.

6. Those Who Mock At Sin
Prov. 14:9 Fools mock at sin, But among the upright there is favor.
Attitude toward sin not what it used to be—a joke.
This is one way the devil deceives people into thinking sin is harmless.
Sin still does what it has always done:
Isa 59:1 Behold, the LORD'S hand is not shortened, That it cannot save; Nor His ear heavy, That it cannot hear. But your iniquities have separated you from your God; And your sins have hidden His face from you, So that He will not hear.
Rom. 6:23 For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.

7. Those Who Leave God Out of Their Plans
Lk. 12:20 But God said to him, “Fool! This night your soul will be required of you; then whose will those things be which you have provided?” Jas. 4:13-16 Come now, you who say, “Today or tomorrow we will go to such and such a city, spend a year there, buy and sell, and make a profit;” whereas you do not know what will happen tomorrow. For what is your life? It is even a vapor that appears for a little time and then vanishes away. Instead you ought to say, “If the Lord wills, we shall live and do this or that.” But now you boast in your arrogance. All such boasting is evil.

8. Selfishness Leads To Forgetting God
Lk. 12:15 And He said to them, “Take heed and beware of covetousness, for one's life does not consist in the abundance of the things he possesses.” 16 Then He spoke a parable to them, saying: “The ground of a certain rich man yielded plentifully. 17 And he thought within himself, saying, ‘What shall I do, since I have no room to store my crops?’ 18 So he said, ‘I will do this: I will pull down my barns and build greater, and there I will store all my crops and my goods. 19 And I will say to my soul, “Soul, you have many goods laid up for many years; take your ease; eat, drink, and be merry.”’ 20 But God said to him, ‘Fool! This night your soul will be required of you; then whose will those things be which you have provided?’ 21 So is he who lays up treasure for himself, and is not rich toward God.”

9. Unfaithful Church Members
Gal. 3:1 O foolish Galatians! Who has bewitched you that you should not obey the truth, before whose eyes Jesus Christ was clearly portrayed among you as crucified?
Gal. 5:7 You ran well. Who hindered you from obeying the truth?
Hindered by Satan:
1 Thess. 2:18 Therefore we wanted to come to you--even I, Paul, time and again--but Satan hindered us.
Foolish: silly, stupid, thoughtless, idiotic, irrational.

10. Must Be Vigilant, Not Foolish!
Eph. 4:27 Nor give place to the devil. 2 Cor. 2:11 lest Satan should take advantage of us; for we are not ignorant of his devices. 1 Pet. 5:8 Be sober, be vigilant; because your adversary the devil walks about like a roaring lion, seeking whom he may devour. Eph. 6:11 Put on the whole armor of God, that you may be able to stand against the wiles of the devil.

11. Those Who do Not Prepare To Meet God
The Wise and Foolish Virgins (Matt. 25:1-12).
What’s the difference in the two groups?
Matt. 25:10 And while they went to buy, the bridegroom came, and those who were ready went in with him to the wedding; and the door was shut.
The Two Builders (Matt. 7:21-27).
One prepared (wise)
One unprepared (foolish)
Have You Been Playing the Fool?