Pacifism is often rejected because it is not effective. Sometimes it has been very effective and other times it has not been. War has a similar track record. Sometimes it seems to have been effective and other times it has not been. Perhaps we could ask which is usually more effective, pacifism or war? Of course this raises up the question of how we define “effective”. Within the context you are talking is it simply stopping the blood-shed? If this is all we are talking about why do we not evacuate the whole area and let ISIS take the land? My guess is most of us will reject this idea. Which means that “effective” means more than just stopping the killings. So what is effective? Freedom and peace would part of those answers for me.
Second pacifism is to be rooted in love. Sure too often people use pacifism as an excuse for cowardice. But I will leave that alone for right now. Pacifism is rooted on Jesus’ command to love our enemy. Certainly there are difficulties. Like how we do love our enemies and love the victims of our enemies? But as followers of Jesus this problem needs to be wrestled with. In cannot be simply ignored. Is it love to drop a bomb on someone? Is it love to stand by and let someone be killed? Both questions need to be asked. Both need to be dealt with. We cannot ignore one because it is hard to answer. I do believe all simplistic answers are removed when struggling with these questions.
Now for the record (and this is why I am not a good pacifist) I think I believe that violence can be used to restrain evil. However I am completely convinced that it cannot bring peace.
A couple of comments on WWII. First, we should note that WWII is the direct result of a “successful” war, WWI. Second, people automatically assume that pacifism would not have worked in this situation. Why is that true? Is there any evidence? An example of a non-violent approach being taken in against the Nazi reign is the Rosenstrasse protest. Which were “effective”. Just because we cannot imagine non-violence working in WWII does not mean we right. After all I grew up in the 1980s when no one could imagine non-violence would over throw any communist nation.
What should we do with ISIS? Not 100% sure. Pray. I find it interesting that many believe they would be more “effective” with a gun then on their knees.
There are a couple of questions that I do ask regarding this though. Why is this the most pressing issue right now? I have friends who tell about their families being killed and murdered in their countries. And this has been happening for years. No news reports. No outcry from Christians that we should invade. Why not? Is it because we have no economic stake in their countries? Which leads me to ask is ISIS an issue because they kill people or because they may possibly threaten our economic status? Where did ISIS come from? They are the result of our invasions into Afghanistan and Iraq. Our “effective” and “successful” wars has led to a problem. Perhaps we should tread very carefully before simply saying invade once again.