Montesquieu

A prince who under­ta­kes to des­troy or change the domi­nant reli­gion in his state is taking a consi­de­ra­ble risk. If his govern­ment is des­po­tic, he runs a grea­ter risk of seeing a revo­lu­tion than through any kind of tyranny, which in these sorts of sta­tes is never any­thing new. The revo­lu­tion occurs because a state does not change reli­gion, ethos and man­ners in a moment, and as qui­ckly as the prince publi­shes the decree esta­bli­shing a new reli­gion.

Besides, the for­mer reli­gion is tied in with the cons­ti­tu­tion of the state, and the new one is not ; the for­mer is com­pa­ti­ble with the cli­mate, as often the new one can­not be. To make it worse, the citi­zens turn away from their laws ; they begin to dis­dain the govern­ment already esta­bli­shed ; doubts about both reli­gions take the place of a firm belief in one ; in a word, it is to give the state, at least for a time, both poor citi­zens and poor belie­vers.