The appearance of the Miracle Monks ensured the Miracle Sect's military strength, but to control this power, besides strict selection, Richard added an additional step of Mind Suggestion.
Through the Magic Equipment engraved with Mind Suggestion, all Miracle Monks will have a seed of loyalty to the Church planted in them.
This seed of belief will grow and take root as the Miracle Monks develop, becoming deeply entrenched. Furthermore, removing this seed requires the cooperation of the Miracle Monks themselves.
That is to say, unless the Miracle Monks face a situation that causes their personality to generate thoughts contrary to the seed of belief, relying solely on external force will not only fail to remove the belief seed but will also strengthen it.
And Richard certainly wouldn't let the Church fall into a state that even devout priests cannot tolerate.