Think of flattery as the opposite of gossip. The latter is something you say behind someone's back that you would never say to his face. Flattery is something you say to someone's face that you would never say behind his back. In other words, you heap praise upon a person, but it is a lie to gain something from them. In writing about false teachers, Jude describes them as: These are grumblers, complainers, walking according to their own lusts; and they mouth great swelling words, flattering people to gain advantage (Jude 16 NKJV). Flattery is sinful because it is based on deceit and covetousness. Therefore, we should never do it.
Absalom, David's son, wanted to be king. So he used flattery. Now Absalom would rise early and stand beside the way to the gate. So it was, whenever anyone who had a lawsuit came to the king for a decision, that Absalom would call to him and say, “What city are you from?” And he would say, “Your servant is from such and such a tribe of Israel.” Then Absalom would say to him, “Look, your case is good and right; but there is no deputy of the king to hear you.” Moreover, Absalom would say, “Oh, that I were made judge in the land, and everyone who has any suit or cause would come to me; then I would give him justice” (2 Samuel 15:2-4). He did what he did for his own gain, so that these people would be persuaded to support him over his father. The text would go on to say: In this manner Absalom acted toward all Israel who came to the king for judgment. So, Absalom stole the hearts of the men of Israel (1 Samuel 15:6). He flattered them to "steal" them away from David. Stealing is a sin.
But also, we should beware when others flatter us because we may believe their lies and be persuaded to do something we ought not. The wise man warns us about those who may flatter us: A man who flatters his neighbor spreads a net for his feet (Proverbs 29:5). Once there was a student who was struggling with his grades in a certain class. He would often visit his professor in his office and tell him how much he enjoyed his class and how good a teacher he was. The student was flattering him so that the professor might feel obliged to give him a better grade. But it didn't work. The student failed the class. He later saw the professor on campus and berated him. So, the student did not mean what he had said to him earlier - he was just trying to get a better grade by flattery. But the professor did not fall for it, being a man of integrity. But what if he had?
Flattery is deceitful praise, and we must not do it, and we should beware of it. But we should not let our avoidance of flattery prevent us from offering a good kind of praise to others. This good praise is not prompted by a selfish motive, but rather a true delight in the good behavior or actions of another. We should praise or compliment others to acknowledge the good they do and to encourage them. God complimented Job (Job 1:8). Paul complimented Timothy (Philippians 2:19-23). The Lord will compliment the faithful at the Judgment (Matthew 25:21,23). Paul told the church in Thessalonica to comfort each other and edify one another, just as you also are doing (1 Thessalonians 5:11).
May we be generous with sincere praise and receive such praise with thankfulness. But let us beware of flattery, so that we neither flatter nor are deceived by it. He who rebukes a man will find more favor afterward than he who flatters with the tongue (Proverbs 28:23).
Brotherly, Jamie