This is a great question. Let me make a few points that will get you started in thinking about this topic.
The events of 9/11 teach us many things. First, it teaches us that for all our advancement and knowledge, some things never change or have a hard time changing. There will be conflict in our world and there is hate in the human heart. In other words, there is something about the human heart that is truly fallen and broken.
9/11 also teaches us that religion is an important issue today. Many people thought that religion would die out by now with all our "enlightenment." However, there is a rise in religious beliefs all over the world. All statistics teach us that fundamentalism is growing in almost all major religions. This tells us that the human heart is religious.