Scripture teaches that it is wrong to strike back or to return evil for evil, whether by immediate retaliation or by taking revenge later. Justice must be done, but this must be left in the hands of God, or of the authorities ordained by God.
OT teaching about revenge
Revenge forbidden in the OT Ge 4:15; Lev 19:18; Dt 32:35; Pr 20:22 See also Dt 19:5-7,11-13; 23:7; Pr 24:29; Jer 29:7.
The “lex talionis” (law of exacting life for life) Ex 21:23-25 This was not a rule for personal revenge but to ensure that judicial punishments were neither unjust nor malicious. See also Lev 24:17-21; Dt 19:18-21.
Personal revenge forbidden in the NT:
1) By Jesus Christ Mt 5:38-45 See also Lk 6:27-36.
2) By the apostles Ro 12:17; 1Th 5:15; 1Pe 3:9 See also 1Co 13:4-5
The evil effects of revenge illustrated in the life of Samson
Alternatives to revenge:
1) Avoiding the problem Ro 12:18; 1Pe 4:8.
2) Evading the attack Mt 10:23; Lk 4:29-30.
3) Accepting the injury 1Co 6:7; Heb 10:32-34.
4) Using the law Ac 22:25.
Forgiving and setting an example Lk 23:34; Ac 7:59-60
Ashes on the head were a sign of repentance. Doing good to one’s attackers may lead them to a change of heart: Ro 12:19-21; Pr 25:21-22
God will avenge his people
Lk 18:7-8 See also Dt 32:43; 1Sa 24:12; 2Ki 9:7; Ps 18:47; Rev 6:10; 19:2.