Instead of replying to several points brought up that have already been discussed, I'll just make this post.
First, I am saddened beyond words that so many Christians have been so overcome with humanism that they no longer believe that one person's soul is more important than millions of people dying a worldly death. Jesus must be weeping in heaven looking down on us right now. Whatever happened to "to live is Christ and to die is gain"? The disciples willingly sacrificed their lives so others might turn towards Christianity. There have been numerous martyrs that have done likewise throughout our history. Paul was willing to go to hell himself (for eternity! imagine that) to save souls. Whether you want to hear this or not, your views are not represented by biblical scripture.
I once heard John Piper's response to hurricane Katrina. The radio talk show woman was asking him to respond to the people who were trying to say that God had nothing to do with it. I don't have the transcript offhand, but he quoted the same verse that I have already quoted here. Scripture is clear: nothing happens apart from the will of God. He is omnipotent, magnificent. He has control over the whole of his creation. It might very well have been caused by man, but God very well could have stopped it if he had chosen to, and he did, since Hitler didn't conquer the world. Piper went on to talk about the tower in the gospel. I will try to recall the story, but I may mess up some details. Forgive me. A tower had fell on a group of Jews and someone had come to Jesus to ask him why it happened. He told them that they were all sinners and that we were asking the wrong question. We should be asking ourselves, 'what mercy the Lord has for letting us to go on living every day despite our sins'.
That, my friends, is the Biblical response to tragedy. If you want to say that God had no part in the Holocaust, then God can do you no good. If he is not all powerful, what kind of God have you placed your faith in? This is a God that wiped out Israel's opposition, flooded the earth, destroyed whole cities. It is not within your power to tell anyone what God did or didn't do. One thing we can be sure of is that the Holocaust did not occur apart from the will of God.