The Australian writer David Malouf was interviewed on ABC radio today. In one of his recent novels, the ancient Greek god Hermes appears. The interviewer noted that Wikipedia entries on the ancient gods get more hits than entries on Jesus, and he may have been wondering whether or not this indicates a resurgence of paganism. Though not a 'pagan', Malouf explained that the persistence of interest in deities, the reason we still feel a thrill when we read the name of a deity in a poem or story, is due to the fact that they personify eternal qualities in human beings and nature. Carl Jung called them Archetypes. Others have likened them to windows through which the Divine may be seen.
From the perspective of universal Selfhood, there is only one being. The Self is a single gem, but it has many facets, and many qualities, qualities which are eternal, which sometimes take a human form in order to evolve the same qualities in human beings.
The Monotheistic prophets emphasised the one-ness of the Self because they observed people worshipping only that aspect of the Self (usually the god of wealth or war) which they believed would satisfy their greed. The founders of Judaism and Islam saw pure archetypes becoming objects of impure desires leading away from Self-realisation, not towards it. Self-realisation requires a simultaneous respect for all aspects of the Divine Self, not just the aspect that suits one's current proclivities.
The deities have survived in monotheistic cultures, as archangels, and the vast Kherubim of the creation.