The history of religious beliefs is a little dodgy over the eons of warfare and the constant attempts to erase parts of history. Various religions literally destroyed what evidence there was of previous religions.
The best I can do is tell you Man worshiped the God Beasts (Animals) before the polytheistic pantheons... Man worshiped the Great Wolf, The Great Serpent, The Great Wyrm, A sea monster, The Mighty Auroch, a Cow, some Dragons, so on and so forth. Later various super powerful deities came into the scene like Zeus, Odin, Thor and others leading campaigns to kill these beasts. Regardless of whether or not the God Beasts were slain their worshiped was systematically outlawed and the Polytheistic pantheons were instated, this was like back in the stone age 10,000 BC. And those beasts were probably worshiped for eons, or vice versa with the Gods in various forms.
As millennia passed the contemporary religions came to fruition through prophets and martyrs and political endorsement.
As far as Gods religion, the best I can tell you is don't be a coward, whore and kin slayer and you should be fine. Most of the gods followers will lick their heels and bide at their every beck and call, don't be like that either.
But even pantheism is dodgy.. You have the Gods and their predecessors the "Giants", but there is little evidence the Giants were worshiped prior to the Gods over-throwing the Giants, but there is evidence some Giants were worshiped, but no pantheons in their entirety, it doesn't look like "organized religion," more like those Giants were infamous throughout the lands.
Hinduism is far more complex, but I never got into it.