1. Religion.
Pros: Going to church has tied communities together for millennia, and if you could just find some better pastors, it could continue for several millennia more.
Cons: Secularly administering religion like a drug to treat social ills is against the precepts of every known religion, due to the fact that we'd all expect missionaries to believe what they're preaching. People who go around saying "I believe because it helps me" but who do not actually believe anything notwithstanding, we all know that's not self-consistent.
2. An amalgamation of historical myths and power structures that tie people together on the basis of perceived brotherhood.
Pros: People love being tied together on the basis of perceived brotherhood, tribal identity has been around a long time, and there is no debating with the idea that it works.
Cons: This is a description of every supremacist organization.
3. You talk to the guy at the barbershop.
Pros: You like to talk to the guy at the barbershop.
Cons: You can't go if you don't have the money for a haircut.
None of these options are perfect... but the barbershop plan is not that bad.