In a perfect world, people wouldn't need gods. But perfect worlds can't exist and sooner or later someone, in trouble, desperate, will pray to the heavens. This is what happens in the beginning of Black & White.
Your new tribe bow before you in awe, and from this moment your prayer power starts to grow. As you carry out godly acts, the belief in you rises and more and more people are convinced that worshipping you is the way forward. But you can be good or evil. You may choose to rule the world as you wish.