Vatican II revolutionized Catholics’ understanding of the relationship between the Catholic Church and other Christian churches. Previously, the emphasis was on separation and on differences. Under the leadership of Pope John XXIII, we came to understand that all Christians are called to be partners in the quest for Christian unity. This challenge involves dialogue and careful listening. The goals of this book are to explain why and how Catholics experienced this shift in understanding, to examine some contemporary advances being made towards Christian unity, to highlight some activities that have fostered these advances, and to leave the reader motivated to deepen his or her commitment to the intention of Christ—that all may be one.

The text provides a brief historical overview of the contemporary ecumenical movement, the main Catholic principles on ecumenism, and an explanation of the practice of ecumenism from a Catholic perspective.