
Some stories remain, people only changing some elements in them, but from time to time there comes a guy that think differently and his stories are so good people are starting to repeat them. Then, one or two generation later, this stories become what people are believing. They consider them closer and closer to real, and they became in time "reality". Religion reality.
Of course, there are many people whose stories are not so good, they are just opinions and people tend to forget them after a time (one or two years).