Sentence:  In a mobile society , congregational health depends on a constant process of recruitment ; this recruitment , however , must follow the pattern of economic integration or it will disrupt the congregation ; therefore , the recruitment or missionary outreach of the congregation will be <WSD>co-optation</WSD> rather than proclamation - like elements will have to be assimilated . 
Meaning of the word marked with <WSD> tags:  the selection of a new member (usually by a vote of the existing membership)