You're either (purposely or accidentally) not listening or not comprehending. I've answered this question repeatedly.
God doesn't support sin. Taking the lives of the innocent is a sin. The terrorists didn't kill the people in the name of Jehovah God; they killed in the name of Allah.
Who created sin, if not for God? If he's all powerful and all-knowing, then he created the universe with sin in it. If you actually read the Bible, then you'd see that God has plenty of killing and suffering that he's lumped on humanity over the years.
Besides that, anybody under Christianity can sin all they want - they just have to ask Jesus for forgiveness, and *boom* sin is gone. Rape a few dozen children in church? No problem - just a quick prayer and all is forgotten, it's like magic!
If Allah is the one granting prayers, not (your) God, then what good is (your) God? He sounds pretty useless.
The Bible says that killing is a sin. Just because killing has happened, or because some people decided to kill (whether in God's name or not), doesn't mean that killing isn't a sin. Whether a particular killing was justified or not... well, you're gonna have to ask God that question. That's way beyond my clearance level. So it's useless to argue with me about why God "let the terrorists win". Ask God when you meet Him.
If only God can judge if it's a sin, then obviously you don't know if it's a sin or not. Here you are again dictating your conditions to God, as if he's going to listen to you above the world?
As far as mass floodings are concerned... I will repeat: Death isn't the big bad boogeyman that we should all fear. Death is simply the transition from this life to the next.
So back to square one then - the terrorists got their wish... oh that's right, God isn't a genie, it's "prayer" - granted, and killed a few thousand people. Since it's no big deal to transition to the next life, then it's no big deal that their prayer wish granting was more powerful than the passengers on the plane, praying that God would intervene and do something.
We're all gonna die. And it is hard to bear when loved ones are taken from us. But death will take us all at some point... whether at the hands of some crazed gunman, or tripping down the stairs, or peacefully in our sleep. Whether one death is more "fair" than others is another of those questions you'll have to ask God. I can't answer that.
Yes we all die - since only God can judge, and only God can answer prayers, then it was pretty obvious that the terrorists praying to kill several thousand people were in favor of God, after all their prayer was granted. Therefore God wanted them to hit the building, according to your logic, since you "can't answer that", but had no problem "answering that" to a bunch of earlier questions as far as what God thinks.
Basically according to your logic, the terrorists are now up in heaven with 77 virgins each, living it up, since God was obviously on their side.