God is sovereign; He has everything under control.
Then why were the mass killing events in history allowed to occur? Also, if this is so, how would this bring happiness? With this kind of thinking, it almost seems like we are just the play things of a mad scientist. Everything under the complete control of one being with unclear motives; your fate is completely set in stone.
The God of the Bible's goal is NOT to make everyone happy, it isn't even to make his followers have happy lives. To him, our short life is just a microscopic blip in eternity, this world is just a test whether or not we love him and choose to spend eternity in his kingdom or choose to live eternity away from him because we reject him. Of course he allows bad things to happen, but every "bad thing" here is only in the finite. That is why trying to analyze God's actions as just or unjust is so ridiculous, we only see in the finite through our own two tiny eyes what looks like it benefits us in this short life. God is not trying to please us in this short life, he is letting us show where we want to spend eternity.
Then what is the need for humans to worship him (it, whatever.)? Why must the complexity of the universe be represented in such a human way? That, in my opinion, does not seem correct.
The universe seems to be just one large process independent of any intelligent management. When I see smaller cycles and processes, I think: why not expand this idea to life? Life is a process. Our environment is a process. We can see that events can occur without any entity interfering.
People have expressed that humanity has free will. Well, what if the universe has complete free will? What proof exists that would show that we (the human race) are special, not unique but special, and that religion is only a way to explain phenomena in a human way?
I am probably writing this out in a much too confusing manner. The above is more my opinion, not something that really be proven correct or incorrect...