Sentence:  The expense of this type of organization in religious life , when one recalls the number of city churches which deteriorated beyond repair before being abandoned , raises fundamental questions about the principle of Protestant survival in a mobile society ; nonetheless , the prevalence of economic <WSD>integration</WSD> in congregations illumines the nature of the Protestant development . 
Meaning of the word marked with <WSD> tags:  the action of incorporating a racial or religious group into a community