I don't even know where to begin with this foolishness, your logic is all over the place.
Tribalism is by definition "us vs them". Religion on the other hand is the closest to a true opposite, a kind of social glue. Especially if they're universalist.
Even tribal pagan/shamanistic religions that are tied very closely to a locality have proved to be the key to diffusing tensions & uniting tribes.
@TenaciousGoat
Famously, the Khazars back in the 8th century realized that their shamanistic pagan religion had hard in-built limits on scalability.
Translation: they could keep the paganism and die under Islamic conquest, or they could adopt a monotheistic religion that provided the strongest possible chance at social cohesion.
They looked at Islam, Christianity and Judaism in depth and settled on Judaism, and then went on to grow & dominate the region for the next 2 centuries.