Do you know Hume's argument for an Established Church? It is quoted in Smith's Wealth of Nations and it is too good not to share. It is Hume at his most impish.
Hume notes that diligence on the part of a worker of any sort depends on, as we would now say, his pay varying with performance. A flat wage not tied to performance leads to an “indolent” worker. An established religion where the clergy are paid a fixed salary by the state will then produce an indolent clergy. And this, for Hume, is a good reason for state establishment, since “this interested diligence of the clergy is what every wise legislator will study to prevent”!
The result of free competition among clergy whose pay depends on the extent and devotion of their congregation, by contrast, will be that:“each ghostly practitioner, in order to render himself more precious and sacred in the eyes of retainers, will inspire them with the most violent abhorrence of all other sects...no regard will be paid to truth, morals or decency in the doctrines cultivated. Every tenet will be adopted that best suits the disorderly affections of the human frame. Customers will be drawn to each conventicle
by new industry and address in practicing on the passions and credulity of the populace.”