How skepticism helps religion

Some people of faith criticize science because it is ever-changing, and therefore cannot be "true" because if it were, it would remain constant.  This is a valid point.  But let us ask ourselves, why is science ever-changing?  It is because people ask questions.  People are skeptical.  The questions that people ask help improve science.  Therefore science becomes better and better over the years becoming a better approximation of the truth.  A similar application of skepticism is what improves religion.

For example, people New Testament times thought that someone with epilepsy was possessed with a devil.  If Christians still taught that people with epilepsy were possessed with devils, they would be laughed at.  Why is this?  It is because of the advance of knowledge.  Skeptics asked, "Are there really devils in these people or is there some other cause?" Now we know that causes of epilepsy and it is unrelated to being possessed with evil spirits.  So, believers can refine their story to make it more believable.  They stop claiming that people are possessed with evil spirits when they're really just epileptic.

People used to believe that the story of Noah was true.  Some people still believe that, but most people will say that it is just a fable or a parable and that their spiritual knowledge to be gained from that.  Again, this changes brought about because of skepticism.  It is not very likely that one man could build a boat that is big enough to fit two of every kind of an animal.  Nor is there any geological evidence that there was a world wide flood.  Questioning religion in this manner helps believers refine their story.  They need to come up with better explanations in order to defend their beliefs against questions.  This makes their religion more reasonable and more believable and therefore helps to preserve the number of believers.

This is how skepticism helps religion.  Their stories in religion which are simply too fantastical to believe, so skeptics question them, and the believers refine the stories or explain them as parables in order to satiate the skepticism.  There are very few people in first world countries now that would believe the religions of 1000 years ago or 2000 years ago because those beliefs are so illogical by today's standards.  And this is all was the result of people asking questions about their religious beliefs or the beliefs of others.