I was going to post a comment in this article, but comments are no longer allowed. I can understand why. This is a very tough topic to deal with.
As a pacifist, I am horrified that a Christian would advocate "wrath and vengeance" as a legitimate means for dealing with ISIS. I can understand the author wishing to make a distinction between individual and governmental responsibility; however, I also note that in the Bible, governments are often singled out and criticized stringently for showing no mercy to the weak and the poor. (See Amos 6:12, Micah 3:1-3, and Zechariah 7:9-14.)
I would like to suggest that even Jesus' Sermon on the Mount could be applied on a governmental level. Imagine: What would happen if on a governmental level, we treated other countries like we wanted to be treated? What would happen if we served others instead of forcing others to bow to our demands?
I know that the United States (to quote President John Adams from his Treaty of Tripoli) "is not, in any sense, founded on the Christian religion," but most countries in the Levant (Middle East) assume that we are a Christian nation (a common misunderstanding, to be sure). So, if our nation acts out in revenge and wrath towards ISIS, how will that bring about peace? How will that make us peacemakers?
What if we, as a nation, would "turn the other cheek?" Yes, someone has hurt us. Yes, someone has killed our citizens. Why don't we break the cycle of violence and show love and mercy instead of "wrath and vengeance?"
Some would say that I am naive in this presumption. They may be right. However, I believe that advocating for peace instead of revenge is preferable and more Christ-like.
Leave vengeance to God. God says it best: "Revenge is my domain, so is punishment-in-kind." (Deuteronomy 32:35)