Thanks for the info about "Imams".
However, you are mostly incorrect about clerics under Christian religions. I'm not a Catholic so someone who is can correct me if wrong, yes, here, the catholic church chooses the clerics (father, priest whatever) for a church.
However, in the US the great majority are Protestants. The Protestant church is totally decentralized. Each individual church chooses to accept their preacher/pastor. They can also dismiss them if they so desire.
In my experience (Presbyterian) all preachers/pastors are graduates of a seminary college. However, I believe that in many small rural areas some baptist preachers/pastors are not seminary college graduates.
But yes, aside from Catholics, we (the people in the individual church) decide who the clerics are.
I think the level of decentralization of Protestants is unknown for the most part. We have no Pope, no Grand Imams, no religious authorities, no Mecca etc. We only have some loose confederations of churches that (mostly) agree to a limited set of religious tenets, the purpose of which is to share resources for common goals. (E.g., support the building of a drinking water project in a 3rd world country.) Only some churches belong to such confederations.
Fern