Sentence:  The inner life of congregations will prosper so long as like-minded people of similar social and economic level can fraternize together ; the outer life of <WSD>congregations</WSD> - the suitability of the environment to their survival - will be propitious so long as the people in the area are of the same social and economic level as the membership . 
Meaning of the word marked with <WSD> tags:  a group of people who adhere to a common faith and habitually attend a given church