Your usage of the word 'unify' here is not relevant to mine.

For any given context, some beliefs will be irrelevant, and some may need to be shared.

In order to enjoy music, you don't need to share the same religion, or even really hold any beliefs in common.

But in order to decide how to run a country, including what rights to uphold, what punishments to enforce, and what things to value, you need to have some common beliefs.

I wrote another response with some similar ideas the other day: https://nebulasaurus.medium.com/no-ideology-philosophy-religion-ever-provides-a-complete-worldview-fae98d02fdf6