The term God itself, going back to the issue in the OP, is just used by cult leaders to differentiate themselves from other cult leaders. In marketing one has to differentiate themselves from the competition so that their business can thrive.
This is partially why the definition of god changes even with christians. From the Yahweh of the bible who is purely monotheistic, to Yaldabaoth the evil God, to Jesus being God, to God being a trinity, to unitarianism, to the JW definition of God. They are all marketing ploys to rally people to their side or to even make the originator of said concept feel special so that they believe they have some new enlightening knowledge of god which makes them the "true" believer who all "righteous" people must follow.
Added to this values must conflict with others to gain support and to benefit the puppeteer, because they exist for narcissitic reasons in the first place.
They cannot unite because then the group is no longer special and then weaker cult leaders cannot compete. So unification is impossible.