Big old machine that is built not on the success of Suriel, but on the disappearance of opposition to the cult of Suriel.
The kingdom is a bureaucratic beast that relies heavily on local authority to function today. Laws are centralized and wielded by the authority of the King whose influence is waning. Religion has taken a step back to let the wants of its different people to the fore. The existence of gods is not questionned, but the immediate needs of the people have reduced the following. Religious power is mostly used to enforce matters of hedge mages.
The narrative the kingdom is built upon is the success of Suriel’s campaign. Some savvy people would say that the disappearance of opposition to the rise of Surielite narrative is what has made it so popular.