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Hastings' Dictionary of the New Testament [1]

This term is employed by Authorized Versionwith considerable frequency to render the group of words καυχᾶσθαι, καύχησις, καύχημα. They are found about 40 times in Septuagint, and about 60 times in the NT (exclusively in St. Paul’s Epistles, except  Hebrews 3:6,  James 1:9;  James 4:16). The forms ἐγκαυχᾶσθαι ( 2 Thessalonians 1:4) and κατακαυξᾶσθαι ( Romans 11:18,  James 3:14) are also found. The group belongs to what Lightfoot (Com. on  Philippians 3:5) calls ‘the tumultuous eagerness of the Apostle’s earlier style’; the words appear most frequently in 2 Cor., where personal feeling is deeply stirred. Whereas in Authorized Versionthey are rendered by ‘boasting’ and ‘glorying’ in about equal proportions, in Revised Version‘boasting’ has almost completely disappeared, and ‘glorying’ is found instead. The only place where ‘boast’ is now found is in  James 3:5 -‘the tongue also is a little member and boasteth great things’; but here the verb is not καυχᾶται but αὐχεῖ, and the idea ‘is properly to stretch the neck and hold up the head in pride, and hence to speak with proud confidence’ (Hort, ad loc. ). ‘Boastful’ still appears twice in Revised Version( Romans 1:30,  2 Timothy 3:2, taking the place of Authorized Version‘boasters,’ and is the equivalent of ἀλαζών, the abstract noun ἀλαζονεία being rendered in  James 4:16 ‘vaunting’ and in  1 John 2:16 ‘vainglory,’ the only two places where it occurs. The ἀλαζών (‘boastful’) has evil associations in both passages-in  Romans 1:30 with those who have been given over to a reprobate mind, and in  2 Timothy 3:2 with the ‘proud,’ blasphemers, and such like. Similarly ἀλαζονεία is found in Patristic literature in lists of vices and corrupt practices-in Didache (v. 1) along with ‘self-will,’ ‘covetousness,’ and others; in 1 Clem. xxxv. 5 bracketed with ὑπερηφανία, ‘pride,’ in such a list; and in Ep. to Diognetus (iv. 6) in conjunction with πολυπραγμοσύνη, ‘meddlesomeness.’ Aristotle saw in the ἀλαζών, ‘not merely one making unseemly display of things which he actually possesses, but vaunting himself in those which he does not possess’ (quoted in Trench, Synonyms of NT 8, Lond. 1876, p. 96). In no such category could St. Paul be placed when he speaks of himself, using καυχᾶσθαι or its cognates, as ‘boasting’ ( 2 Corinthians 7:14;  2 Corinthians 8:24;  2 Corinthians 9:4), The Revised Version, however, has replaced the word by ‘glorying,’ except in some cases where it uses ‘rejoicing’ ( Romans 5:2;  Romans 5:11, but in  James 4:16 ‘rejoice’ of Authorized Versionhas also given place to ‘glory’). ‘Glorying’ (or ‘boasting’) ‘in the law,’ or ‘in works’ as a ground of acceptance with God, or ‘in men’ as watchwords of sects or parties, is condemned by St Paul ( Romans 3:27,  Ephesians 2:9,  1 Corinthians 3:21). But the word expresses well the high level at which he lived, exulting in Christ Jesus. He gloried in the Cress ( Galatians 6:14), in free grace ( Romans 5:11), in an approving conscience ( 2 Corinthians 1:12), in his independence as an apostle ( 2 Corinthians 11:10), in his convert ( 2 Thessalonians 1:4), and above all in Christ Jesus ( Romans 15:17) and in God ( 1 Corinthians 1:31), in the spirit of the Psalmist ( Psalms 44:8), and of the Prophet ( Jeremiah 9:23) who said in the name of God, ‘Let not the wise man glory in his wisdom … but let him that glorieth glory in this, that he understandeth, and knoweth me, that I am the Lord.’

T. Nicol.

Baker's Evangelical Dictionary of Biblical Theology [2]

The concept of boasting is found frequently in both the Old and the New Testaments. The object of boasting determines its nature. If it is God or the commendable qualities of others, then boasting can be described as proper; if it is wrongly applied to oneself, then it is improper. The Hebrew word mahalal [מַהֲלָל] is sometimes translated "boast." The basic meaning of the word is "to praise, " as in the English word "hallelujah, " which means "praise Jehovah." The Greek word kauchaomai [Καυχάομαι] ("to vaunt oneself") is used in the New Testament. Like its Hebrew counterpart, it is used in both a good and a bad sense.

Proper Boasting In   Psalm 44:8 the sons of Korah confess, "In God we make our boast all day long." There is no higher or more appropriate form of boasting than this. The Hebrew word mahalel [מַהֲלָל] also conveys the idea of chanting loud praises. Some scholars have suggested that the loudness of the praise was intended to drive away evil spirits, but that is unlikely. The hampering of Satan, however, may be a byproduct of praise since Satan cannot accomplish his purposes where God is exalted. It should also be pointed out that included in praising God is the joy that we experience in doing so.

Boasting about God is one of humankind's most profitable activities. Jesus told the woman at the well that the Father seeks our worship ( John 4:23 ). Both anthropologists and psychologists tell us that human beings invariably imitate what they worship, so the end result of boasting in God is the sincere aspiration to be like him ( 2 Corinthians 4:18 ).

The Scriptures encourage us to engage in proper boasting or praise of other human beings: "Let another praise you, and not your own mouth" ( Proverbs 27:2 ); "a woman who fears the Lord is to be praised" ( Proverbs 31:30 ). Paul boasts in the churches when he can ( 2 Corinthians 7:14 ), and our Lord himself commends six of the seven churches to whom he speaks in the Book of Revelation. Proper boasting in others is a source of encouragement in the body of Christ. In addition to boasting in others, Paul also boasts in hope of the glory of God ( Romans 5:2 ), sufferings ( Romans 5:3 ), God ( Romans 5:11 ), the Lord (Christ) ( 1 Corinthians 1:31;  Philippians 3:3 ), his infirmities ( 2 Corinthians 12:9 ), and the cross ( Galatians 6:14 ). These uses of kauchaomai [Καυχάομαι] basically convey the idea of "rejoicing" or "glorifying" as the word is translated in most versions.

Improper Boasting The wrong way to boast is to boast in ourselves. After saying that we have received everything from God, Paul poses the question, "Why do you boast as though you did not?" (  1 Corinthians 4:7 ), clearly implying that any time we boast in ourselves we are taking praise that belongs to God alone. Paul also mentions the fact that we should not boast in other people ( 1 Corinthians 3:21 ), in the sense of putting them above Christ. We should also not boast in appearances rather than what is in the heart ( 2 Corinthians 5:12 ). We are warned not to boast beyond proper limits ( 2 Corinthians 10:13 ). We must refrain from presenting an exaggerated description of ourselves. In the great passage on grace as the means of salvation Paul describes salvation as not being "by works." Because it is God's gift, "no one can boast" ( Ephesians 2:9 ). Therefore, we are not to boast as if we were self-sufficient. James reminds us that all arrogant boasting is evil (4:16).

Boasting in oneself is an expression of pride. Those who sin express arrogance by implying that they can successfully violate the laws of Almighty God. Paul describes the arrogant and boastful as "God-haters" ( Romans 1:30 ). Humility is defined as the absence of arrogance and boasting and is characterized by submission to God's will. The absence of self-exaltation and the attitude of humility place one in a position of being blessed by God ( Isaiah 66:2 ).

In his discussion on the sinfulness of the human race Paul concludes that boasting is excluded on the principle of faith ( Romans 3:27 ). The entire scope of biblical teaching about boasting is best summarized in a statement made by Jeremiah and later quoted by Paul: "Let him who boasts boast in the Lord" ( Jeremiah 9:24;  1 Corinthians 1:31 ).

Alan N. Winkler

Bridgeway Bible Dictionary [3]

One result of pride and self-sufficiency is that people boast of their achievements instead of giving honour to God ( Deuteronomy 8:11-14;  Jeremiah 9:23;  Daniel 4:30;  1 Corinthians 4:7;  James 4:13-16). Such boasting is hateful to God and will bring from him a humiliating judgment ( Isaiah 10:15-16;  Isaiah 37:23-29;  Luke 18:10-14; cf.  Matthew 6:1-4;  John 12:43).

Confidence in self is one of the things that prevent people from coming to God and receiving God’s salvation. People cannot earn salvation as a reward for any good deeds they might do. They can only receive it as a gift that God gives freely to those who trust in his grace. They therefore have nothing of themselves that they can boast about ( Romans 3:27-28;  Romans 4:1-5;  Romans 9:30-32;  Ephesians 2:8-9). If they boast at all, they boast in what God has done, not in what they have done ( Jeremiah 9:24;  1 Corinthians 1:31;  Galatians 6:14; see also Pride ).

The Bible records one occasion on which the apostle Paul boasted, even though he knew it was not the sort of thing a Christian should do. But his purpose was to answer certain people in Corinth who opposed him. These people too easily believed the boasting of men who set themselves up as super apostles ( 2 Corinthians 10:8;  2 Corinthians 10:13;  2 Corinthians 11:1-5;  2 Corinthians 11:16-21;  2 Corinthians 12:1-11). By contrast, most of the things that Paul boasted of were things that the normally boastful person would be ashamed to speak about, namely, his personal humiliations ( 2 Corinthians 11:23-30).

King James Dictionary [4]

BOASTING, ppr. Talking ostentatiously glorying vaunting.

BOASTING, n. Ostentatious display of personal worth, or actions a glorying or vaunting.

Where is boasting then?  Romans 3

Webster's Dictionary [5]

(1): (p. pr. & vb. n.) of Boast

(2): (n.) The act of glorying or vaunting; vainglorious speaking; ostentatious display.