Synonyms for Ecumenism (same or very similar meaning)
WordNet sense 1 (a movement promoting union between religions (especially between Christian churches)):
oecumenismWordNet sense 2 ((Christianity) the doctrine of the ecumenical movement that promotes cooperation and better understanding among different religious denominations: aimed at universal Christian unity):
ecumenicalism, ecumenicismFrom the ODE community, based on WordNetadd/edit