Why, in snake mythology, are snakes known as mythical creatures?
Snake as a symbol of Power and Immortality.
In Roman myth, we learn of Mercury breaking up two battling snakes with his staff. The two serpents then entwined themselves around it. That became a symbol of peace. Today it is the emblem of the medical profession.
Mexican myth tells of Quetzalcoatl, the feather-clad serpent. He was a half bird, half snake, which was to represent the totality of heaven and earth. However, Quetzalcoatl is often perceived as the god of life and civilization. The feathered serpent god does personify the forces of nature, therefore is both capable of evil, as well as good.
The snake as a symbol of Evil
In the first book of the Old Testament, the serpent is portrayed as the tempter, Satan. He is said to have tricked Adam and Eve into eating the forbidden fruit from the tree of knowledge. By eating the apple, they committed original sin, causing man's exile from Paradise.
Even Greek myth treats the serpent as a figure of evil. Many beasts and evil figures were part snake. For example, Medusa, the snake haired witch, who if any man looked into her eyes would turn to stone.
In Catholic legend, we are told of Saint Patrick, who drove all the snakes out of Ireland - Again, some negativity towards the snake.
Snakes in religious practice.
In a Christian practice, certain groups of fundamentalists in Appalachia and southeastern U.S. handle snakes as a testament of their faith. The practice began in the early part of the twentieth century with Tennessee evangelist George Hensley, who was caught by a passage in the Book of Mark which said, "...They shall take up serpents, and if they drink something deadly, it shall not hurt them." Hensley caught a rattlesnake and began using it in his sermons with the belief that his faith in God would protect him from harm. Although there is a risk, many people have bitten and some have died in this practice. A rattlesnake killed Hensely himself during one of his sermons.
Snakes as Creator
The aborigines of Australia worship a rainbow serpent named Kurrichalpongo. They believe that it created the world and whose eggs hatched the mountains onto the earth and the trees into the ground.
Perception of the snake tends to be dependent upon the region. Indigenous peoples tend to revere the snake as a powerful ally, sometimes a god, whereas the western tends to hold the snake in contempt and fear.