The phrase "old mythology" refers to ancient stories, beliefs, or legends that were passed down through generations. It usually describes the traditional and often magical tales of gods, heroes, and creatures from a long time ago. Full definition
Clearly ancient eastern, non-Jewish conceptions influenced this Baptist movement; old mythology of Persia or Babylon perhaps also influenced the Baptist's preaching of the coming Judge. (religion-online.org)
Religion on the other hand is pretty much the opposite — dogmatic clinging to 2,000 + year old mythology with charlatans adding inane explanations of the unproven, and unprovable. (religion.blogs.cnn.com)
Harry Potter's theology is a very old mythology and is part of a very long tradition of fantasy - fiction based on Norse legends. (religion.blogs.cnn.com)