Regret
3338 METAMELOMAI (6): meta = after + melw = to care about; after-care about: to be concerned about afterwards. In Mt.27.3-4 Judas cared afterwards because "he was condemned." Although his "after-care" included both a change of mind (I have sinned, betraying innocent blood.) and works (he returned the thirty pieces of silver), his regret was short-lived in that it was neither a long-term change of mind nor a change of life (metanoia), as evidenced by his subsequent suicide. Thus, although both metamelomai and metanoia include a change of mind accompanied by appropriate works, metam[lomai is brought on by the urgency of the moment and (in this case, at least) is a short-term event. Accordingly, in 2Co.7.8-10 (esp.v.10), "godly grief" is a means of working a long-term "change of mind" (3341 metanoia), not a short-term "regret" (metamelomai) which has no lasting effect. However, in Mt.21.32 even a short-term "regret" could perhaps have led the chief priests and older men to belief. Comp. "unregretted" (0279 ametamelftos).
REGRET Mt.21.30,32; 27.3. 2Co.7.8,8. Heb.7.21.
3340 METANOEO (34): meta = after, later (implying change) + noeo = to perceive, understand; to understand afterwards, to change one's mind to the extent that one changes his life, to repent. Always used in a good sense in God's FCR. In Act.3.19, metanoeo is described as a "turn" (1994 epistrepho); evidently a turn away from "wrongdoing." In Act.26.20 metanoeo includes a "turn" (epistrepho) to God and a demonstration of this "turn" by "doing worthy works." In Rev.2.5 it pertains to a group of called-ones going back to doing their "first works." In Rev.9.20-21 metanoeo includes a change of life from idolatry, murder, etc. Accordingly, metanoeo includes much more than just a change of mind, but a change of life or change of self.
In parallel passages, "if he listens to you," in Mt.18.15, is equivalent to "if he changes his mind" (metanoeo) in Lk.17.3, showing that both a thought process and a decision to change are included. See "regret" (3338 metamelomai) which involves a short-term "change of mind."
Comp. "to renew" (0365 ananeoo) as it concerns "be renewed in the spirit of your mind" in Eph.4.23. Ambiguous use of the word "repent" precludes its use to translate metanoeo. See "regret" (3338 metamelomai) for comparison of "regret" and "change one's mind (repent)."
CHANGE ONE'S MIND Mt.3.2; 4.17; 11.20,21; 12.41. Mk.1.15; 6.12. Lk.10.13; 11.32; 13.3,5; 15.7,10; 16.30; 17.3,4. Act.2.38; 3.19; 8.22; 17.30; 26.20. 2Co.12.21. Rev.2.5,5,16,21,21,22; 3.3,19; 9.20,21; 16.9,11.
3341 METANOIA (22): meta = after + noema = thought; an after-thought, a change of mind, repentance. The idea of a change of of mind can be seen clearly in Heb.12.17, where Esau "found no place for a change of mind" in his father, Isaac.
In Act.20.21 metanoia is a change of mind or attitude towards God. In Act.26.20 "works worthy of a change of mind" are enjoined (c.f., Mt.3.8, Lk.3.8), showing that metanoia results in beneficial activity. Lk.15.7 (cf., Mt.5.32) states that wrongdoers need to change their mind, not those who are just, showing that metanoia includes a change for the better. God gave men a "change of mind unto life" in Act.11.18, evidently in the sense that the kindness of God leads humans thereto (Rom.2.4, cf. 2Pe.3.9) by allowing them an opportunity for a change of mind. In Heb.6.1 metanoia involves a change of life from dead works. "Grief or sorrow" (3077 lupe) is not the same thing as a change of mind but can lead one thereto if it is "according to God" (2Co.7.10). In 2Pe.3.9 metanoia is in a sense the opposite of perishing (0622 apollumi). More than a change of mind is suggested by the above contexts, showing that a change of heart or change of self is included. Ambiguous use of the word "repentance" precludes using it to translate metanoia. Used with "turn around" (1994 epistrepho) in Act.3.19 and 26.18.
CHANGE OF MIND Mt.3.8,11. Mk.1.4. Lk.3.3,8; 5.32; 15.7; 24.47. Act.5.31; 11.18; 13.24; 19.4; 20.21; 26.20. Rom.2.4. 2Co.7.9,10. 2Ti.2.25. Heb.6.1,6; 12.17. 2Pe.3.9.