Which side does God take?

I don't think God takes sides at all. There are certainly some wars which are generally seen to be 'right' against 'wrong' - the war against Hitler (and his supporters) is certainly generally regarded as one of those - but who is 'right' and who is 'wrong' in most conflicts is a matter of human opinion and to assume that it is also God's opinion amounts to anthropomorphism if not to blasphemy. God is often seen and described (especially by Christians) as a 'loving Father'. That He does love His creation is, I think, denied by few religions but most religions attempt to describe Him in human terms - as if He were human, which He is not. He does not love or hate or take sides in the way that humans do. Even though we are said to be 'made in His image', that neither makes us Gods or makes our Creator human, so we cannot expect Him to necessarily take the side of what we are convinced is 'right' simply because we are convinced that it is so.

Billions of people with billions of lessons to learn, interacting with billions of people. The dynamics of it all are incredible. You can be sure good will come out of it all. If only we had a wider vision. Of course, isn't it all too much to see for us mere mortals?? Man's view is that the one who wins the war is who God favors. That is too easy an answer to cover the entire truth.

He does take sides! He doesn't approve killing no matter what and war is not an exception. God is love and he would never encourage any form of violence.