Ecumenism, from the Greek word “"oikoumene"”, meaning “the whole inhabited world” (cf. Acts 17.6; Mt 24.14; Heb 2.5), is the promotion of cooperation and unity among Christians. The Union of Christendom is a traditional Catholic view of ecumenism; the view is that every Christian church is destined to return to the unity which it has broken. As the largest, most widespread and oldest Christian denomination, the Catholic Church saw itself as a trunk from which other Christian denominations had broken off. This would mean that Christian unity was a reality, present in the Catholic Church.