Whether there is a God or not, simply accepting it to be a fact has never been a catalyst for true intelligence. You can certainly learn facts and memorize, you can be a virtuoso or be a billionaire with brilliant financial strategies and even create an elaborate argument whether God exists or not; but the actual process of creating more use of the objective conscious brain, means going into the fire, facing your fear of the unknown and facing everything you think you know, over and over, especially the belief in God.
Although being very comfortable, believing in anything, outside of yourself and what is possible for you, has never been a catalyst for the evolution of humanity. It has been a way to control the uneducated masses and give a platform of relative civil cooperation, but not for actual human evolution.
That is why I say: Religion is like Chemotherapy, the right dose will help you, but after that anything more will kill you.
Other then your own discovery of this truth, look at what history alone has born out:
Even people like Galileo, Leonardo da Vinci, Einstein, Copernicus, etc., who had some sense or connection with the concept of there being a God, did not allow that to stop them from questioning and challenging what that means. You could say that their contributions to humanity were about expanding the understanding of the infinite possibilities of what the universe and God could be.
It has never been about just accepting some human made rules, regulations and rituals. It was never about the human concept of worshiping and praying to God. (The need to be worshiped is a human frailty not a Godly one). The progress of human intelligent evolution has always been about taking responsibility for your life and your decisions as if there is no God except the little God that resides in the kindness of your own heart. It has been about working to find solutions and inventions to help the world, rather than pray for it to miraculously come out of the sky.
Wars, slaughter and prejudice has always come from the determination of humans trying to impose their limited definition of God and his supposed rules to live by on others.
So when you condemn the Islamic extremists and want to change their beliefs, as horrific as they are, look at yourself first and see how hard it is to change your own beliefs or even recognize that you need to in the first place.