Wrath belongs to God, not to us. For this reason, we must keep a close eye on our anger and dwell in the truth of God's Word daily to provide fertile ground in our hearts for the Spirit to produce the fruit of gentleness, peace, and self-control in us.
When we become eager to enact God's wrath through personal vengeance, it's often because we distrust God's ability to deal with injustice Himself. Or we distrust Him to do it in a way that satisfies us. When we lash out, fight back, take up zealous causes, angrily pontificate, feud on Facebook, tsk-tsk on Twitter, and berate on blogs, aren't we, in essence, saying God needs us to set people straight? All too often what we're really protecting isn't God's honor, but our reputation or influence.
Jesus' approach to personal wrongs would have us conquer the injustice by embracing its satisfaction at the cross. So instead of attacking the guy who takes our shirt, we offer him our coat, too. I'll admit that Paul's questions in 1 Corinthians 6:7 sting a bit: "Why not rather put up with injustice? Why not rather be cheated?"
If the cross is true, if God is sovereign---why not?
Friends, do not avenge yourselves; instead, leave room for His wrath. For it is written: Vengeance belongs to Me; I will repay, says the Lord (Romans 12:19).
The reality is that whatever wrath remains to dispense after the satisfaction of the cross will be dispensed by Jesus Himself upon His return. The Book of Revelation doesn't portray a passive, excuse-tolerating King who gives everybody a hall pass whether they love Him or not. Instead, He arrives on a white horse with a sword, vanquishing His enemies. But He does this, not us. So if we will truly trust that vengeance is His, that he will repay, we have all the power in the Spirit to let it go.
And honestly, that's what some Christians need to do right now: Let. It. Go. Because God won't leave any loose ends.
-- Wilson, Seven Daily Sins: How the Gospel Redeems Our Deepest Desires (Nashville: Threads, 2012), 112-113.