Sentence:  Churches can be strengthened through this process of co-optation so long as the environs of the church provide a sufficient pool of people who can fit the pattern of economic integration ; once the pool of recruits diminishes , the congregation <WSD>is</WSD> helpless - friendly contacts no longer keep it going . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)