As I have been working through this area in Matthew 5 which deals with retaliation and loving our enemy, it really hit me that one of the reasons God wants us to reserve vengeance for Him is that we can't handle it. See, in my flesh I get bitter and angry when people mistreat me (or I feel like they do), when I try to "get even" it starts to shape my character. We cant handle dealing out vengeance without it corrupting us....it poisons us with bitterness, hate, mistrust. Only God can handle vengeance without it affecting Him. Being perfectly Holy, Rightous, and Just, He can administer wrath without it affecting Him at all. Part of the reason He wants us to leave vengeance for Him is that He loves us and doesn't want us to be damaged.......something to think about.