All man made systems fall victim to the very fact that they are man made.
Science as a system always challenges itself, it welcomes change, testing and retesting theories, many scholarly minds coming together and working relentlessly for answers.
Your
reaction seems to imply that you might not believe that all religions are man made, but all research I have been made aware of point to it. Sure, most derive from stories of a prophet or God inspiring the writings, but proof for that is never provided.
Religions are formed on dogma, and once it gains momentum does everything it can to build on the mystery of it all and struggles against change. Many religions will branch off from the original one, with more emphasis on certain passages, or slight variations, but not much changes.
Religion has always used the gaps in science as one of the main proponents to proof of Gods existence, then science fills a major gap, and then they grasp unto some other gap in knowledge.
There is not a 50/50 probability for and against the existence of God(s), the evidence and logic behind a creator is less then the probability of no God, and that we are the end result of natural selection, not supernatural will.