Love has its place, as does hate. Peace has its place, as does war. Mercy has its place, as do cruelty and revenge. The Torah dons sackcloth over the distortion of the concept of revenge, which has become a target for the arrows of all Jewish Hellenists and worshippers of the alien culture, as if revenge were negative and evil by nature.

The very opposite is true! No trait is more justified than revenge in the right time and place. G-d, Himself, is called Nokem, Avenger: "The L-rd is a zealous and avenging G-d. The L-rd avenges and is full of wrath. He takes revenge on His adversaries and reserves wrath for His enemies" (Nachum 1:2). Our sages also said (Berachot 33a), "Shall we say that even revenge is great because it appears between two names of G-d? 'A G-d of vengeance is the L-rd' (Psalms 94:1). Rabbi Elazar responded, 'Indeed. Where revenge is necessary, it is a great thing'" [see Rashi].

"It is a great thing!" It is a great mitzvah to take the revenge of the righteous and humble the evildoer. Whoever forgoes or rejects such an opportunity is cruel, and he denies belief in G-d. As King David said (Psalms 58:11-12):

"The righteous man shall rejoice when he sees the vengeance. He shall wash his feet in the blood of the wicked. Men shall say, 'Verily there is a reward for the righteous. Verily there is a G-d Who judges on earth.'"

This is the secret of the greatness and holiness of revenge. It explains why it is a mitzvah and why the righteous are joyous when they see it carried out. When injustice is done on earth, when the kingdom of evil takes control and stifles the righteous and the innocent, it is only natural for a person to ask G-d, "Where are You?" In a period of Divine concealment, doubt and heresy burgeon forth, as it says (Deut. 31:17): "I will hide My face from them, and they shall be devoured. Many evils and troubles shall come upon them, so that they will say on that day, 'Are not these evils come upon us because our G-d is not among us?'"

The explanation of many of the commentaries, that this verse refers to Israel's repenting, does not seem valid, for if so, why does Scripture immediately reiterate, "I will surely hide My face" (Ibid., v. 18)? Rather, the explanation is that Israel will explain the lack of G-d's presence not as His intentionally hiding His face, but as testimony, so to speak, that G-d is incapable of helping or that He does not exist, G-d forbid. The evildoer's victory is the very worst profanation of G-d's name, because it implies the defeat or impotence of G-d. Of this, King David said (Psalms 44:23-25):

"Nay, but for Your sake are we killed all the day. We are accounted as sheep for the slaughter. Awake! Why do You sleep, O L-rd? Arouse Yourself, cast us not off forever. Wherefore do You hide Your face...?"

Thus, when G-d stops hiding His face and actually "awakens... like a mighty man recovering from wine, and smites His enemies" (Psalms 78:65-66), when He takes the revenge of His people and of Himself, He thereby sanctifies His name, proving to the world that Israel indeed has a G-d and that He lives and endures. The victory of injustice and wickedness is ostensible proof of G-d's absence from the world, and there is no greater profanation of G-d's name. By contrast, G-d's victory and revenge over His enemies, the evildoers, prove to the world that "verily there is a G-d Who judges on earth!" (Psalms 58:12)