In summary...
1) we believe in god simply because human life, this world and the universe we live exhibits complexity, designs and follows fundemental laws, and we believe these 3 qualities is the reflection of the divine. We don't believe or agree that complexity and design comes about through random chance events. Hence we dont believe in biological evolution which brings about life, so you can say we take the position of the creationists. So this position comes from logic and reason.
2) Now after believing that there is a divine creator, ie a watcher maker behind the clock, we believe this being holds the key to the explanations we seek eg why are we here, what is our purpose, is there life after death etc. So believe that god has given every generation of humanity these answers through his prophets, ie men who he chose to communicate and pass his message onto us, and several of these messages/guidelines/instructions is what we refer to as holy book, ie god's law. And this field is the area of what we call 'religion'.
3) It is good for any free thinker to study other religions and try to obtain the truth, ie if there is a god, then which is the right religion, so i do agree to study non abrahamic religions is a good path of study. However, this is for every individual to consider. In islam, generally other ideologies and belief systems are mentioned about, this occurs in the quran, through the prophet and later early generation scholars.
I do agree with you that superstitions and irratinal fears should be eliminated, and in Islam, there is great lengths taken to remove mythological beliefs, in fact that is one of the principle reasons why we believe the prophet was sent ie to put a end to all other deviated or irrational beliefs. As for the scientific approach, we believe scientific fact and religion will always go hand in hand, ie will never be a contradition, if there is, then this is a error in the scientific approach/theories of the community.
Finally, thanks for your posts/comments in this topic, faith or disbelief (ie rejection of faith) is indeed a personal decision every individual makes, lets try respecting each other's position as we are human beings and need to get along in this small planet.