There are two types of social force: physical violence, and attack on reputation (shaming). However imperfectly, we instantiated The State as a monopoly on violence, subjecting violent force to The Rule of Law; while the success of that enterprise is hotly contentious, it's fair to say it works at least sometimes (exonerating some innocents who might simply be killed under pure tribal dynamics; allowing some who are…
In many ways the Church was the old institution of moral power- an attack on reputation could be mitigated through confession and repentance, with the confessor acting as a judge would for the State. Of course once the Church had its own reputation crisis it started to crumble from the top, and nothing has really taken its place.
They serve as a "conscience of the nation".