Exactly what is it you are not believing in? What is "God"?
Have you ever discussed the Lord of the Rings with a Tolkien Fan? They know better than you do exactly what Eru Ilúvatar is supposed to be able to do and what Eru's nature is. But that's fine - you don't need to know all the details before you say "I don't see any reason to believe that Eru exists in real life." Just knowing the process by which a story was written about Eru is sufficient.
There are many supreme deities: Ar, El, Dyaus, Ahura Mazda, Kartikeya, Teshub, Kugu Jumo, Baiame, Ghmerti, Unkulunkulu, Chiminigagua, Endovelicus, Amenominakanushi, Angwusnasomtaka... the list goes on and on.
And these deities tend to have certain attributes in common (from Wikipedia
Creation: Most of these gods derive their power from the fact that they created the world, formulated its laws and/or created life forms notably humans.
Divine Wisdom: Some Kings of Gods possess superior wisdom and clairvoyance, compared to most beings.
Conquest, Law, Justice, Order, Time and Fate: Most kings of gods have the ability to control the events of battle and grant victory to those who deserve it. They are seen as paragons of law and promote order. They are seen as powerful manifestations of their respective civilizations. Some gods either possess great skill in war or tremendous physical strength. Some of them have some control over time and regulate it with seasons.
Actually there's a couple more strong correlations:
God of the Sun, Daylight or Celestial Fire: Some kings of gods are associated with the Sun, as it is life giving and is a powerful symbol of order. They are said to be in charge of celestial fire which are purifying by nature.
Dominion over the sky: Many such deities hold control over all aspects of the sky, such as weather, rain, thunderstorms, air, winds and celestial objects like stars. They use lightning bolts as personal weapons.
But do you believe Odin exists? Was it necessary for you to carry out extensive research on what those who follow Odin (and he does still have followers) think, before deciding whether to believe or not?
