Religion is a powerful influence on all people. Whether you yourself subscribe to a body of religious doctrine or you are an atheist you will none the less know about 'God' and will undoubtedly have opinions (or just the one opinion) on the subject.
There is a fundamental reason for this. We have an evolutionary instinct which induces a fear of the unknown. This, in the distant past, manifested itself quite differently than in our modern, 'enlightened' age. Where we react with skepticism, empirical experiment or some belief in divine inspiration and justice (which seems to be a waning reaction. Modern monotheistic religions seem to me to be the final throw by an archaic mindset... this is not an attack on religion, for it is undoubtedly a moral guide which when adhered to with sense and clarity can help an individual or community lead a fulfilling and 'good' life.) the ancients reacted with stories, allegory and imaginative descriptions of primeval forces which they could not fully comprehend.
The study of mythology is therefore the study of the anthropology of the mind. One can plainly see the hopes and fears of a race of people who essentially are the same as us; seperated by a comparitively negligible period of time and certain scientific advances.
Mythology is the reaction of our pagan ancestors to those aspects of the world that they couldn't explain. It cannot be discounted for being steeped in superstition, stupidity or lack of understanding or awareness, for those people who believed in myths and legends were also those people who began the practice of science, mathematics, philosphy, democracy; those fundamental areas which we believe civilisation consists of.
There are still aspects of the world and universe we inhabit that we can't explain, perhaps black holes are the pit of tartaris, perhaps at the centre of the universe is a golden tree or a mountain of fire and ice where an omnipotent being orchestrates the forces of nature. We may never know. But if the ancients felt the need to explain the world through myth then we should attempt to understand those myths, so that we can better understand the minds of our ancestors, and ourselves.