If he knows all, why does he not intervene before atrocities happen?
I DON'T know! :-) I'm not God.
Ok, that was a cop out.
If God was to stop ONE atrocity, then He would need to stop ALL atrocities and not allow any of them. However, we do have free will, which God allows. It is not logically necessary that since God HAS not stopped evil and suffering in the world, that He CANNOT.Biblically speaking, pain and suffering are the results of sin in the world. Adam, who represented all humanity as well as creation, rebelled against God and brought suffering into the world. Ultimately, we can't know all the reasons why God allows suffering, we just know that He does. But there are various ideas:
1. Free will is allowed by God, and this leads to suffering at the hands of people.
2. God has a greater plan. He allowed Christ to suffer for the benefit of others. They are shown that they are lost without God in their lives, and it leads them to accepting Jesus as their only means for salvation.
3. He allows some suffering for a greater good: Sometimes we learn our greatest lessons after having suffered the consequences of our actions -- and this is good. Not that all suffering leads to good, but some does. And as above, it can lead us to acknowledging that we need Jesus' sacrifice.
4. It's the result of sin and our own conscious separation from God.
5. It serves as a warning: Evil and suffering in the world can serve as a warning against breaking God's law and then people can see the necessity of following God's truth.
6. It proves the point that evil and suffering in the world prove that rebellion against Him brings pain and suffering.
7. And the BIG one...who knows...
Everything brings us to the point of realizing that humans will never end suffering. It's impossible. Any promised human utopia cannot be realized. There will always be suffering.
Unless...