I've met Joel Rosenberg a couple times. He used to write for World Magazine before he wrote a bestselling novel, and World posted a comment from him yesterday on their blog. Before he wrote for them, he was a student at Syracuse University, where I'm currently working on my Ph.D. I've met him a couple times due to my involvement with a Christian organization that he was involved with when he was a student here, and we have some common friends because of that.
He responds to this statement by Nick Berg's father:
My son died for the sins of George Bush and Donald Rumsfeld. This administration did this.
I grieve and pray for this man and his family. No one should have to suffer what they are suffering now.... But Mr. Berg's outrage at the Bush administration is both misguided and offensive. Nick Berg didn't die because President Bush sent military forces into Iraq. President Bush sent military forces into Iraq because innocent people like Nick Berg were dying every day. And many more would have died if Saddam Hussein had been allowed to continue his reign of terror unchecked.
This seems to me to be the right response, with one caveat. It may be that this particular man wouldn't have died had Bush not sent forces into Iraq (and thus I think it's technically false to say that he didn't die because of Bush and Rumsfeld). Still, people like him for similar enough reasons were dying, and that sort of thing would have continued. Bush's reason involved, among other things, wanting to stop such things. They didn't stop entirely, but it's nothing like the way it was when Saddam Hussein was in power.
Now I do want to make a philosophical point about the kind of causal statement often made in this kind of context. There are two general sorts of view about causation. One approach includes the counterfactual model. To determine whether X caused Y, you look at what would have been true had X not occurred. If Y would also not have occurred, then, barring other factors that might changed your judgment, X caused Y. On this model, Bush and Rumsfeld did cause Nick Berg's death. Of course, I've already caused my three children's deaths according to this sense of 'cause'. Am I morally responsible for their deaths? That at least partly depends on how they will die. I caused their deaths, on this model of causation, simply because they couldn't die if they never existed. Since they wouldn't have existed without very specific actions by me at exactly the right time, I caused their deaths. That says nothing about whether I'm morally responsible for it. Other factors come in for that. Nick Berg's father commits the same fallacy as someone blaming me for my children's deaths. He needs to say more to show that Bush and Rumsfeld caused his son's death in the right way necessary for moral blameworthiness.
The other sort of model of causation requires something stronger than this simple counterfactual dependence. The different versions vary greatly, but all of them would require more than what Nick Berg's father said to show causation. So this sort of statement is either wrong or irrelevant, depending on which sense of 'cause' you have in mind (and I think the English word 'cause' is probably rich enough to include both senses in different contexts).