The word “ecumenical” derives from the Greek word oikos, house. Ecumenical concerns and activities have to do with what we may call the “household of Christianity.” In spite of numerous differences among groups of Christians, we may still say that we live in a household in which Jesus is present. It may be a disorderly household, but Jesus is the head of the household.

Because all Christians profess faith in Jesus, we have to watch our language when referring to fellow Christians of non-Catholic ecclesial communities. It is not correct to state, for instance, that a Baptist or a Lutheran or an Episcopalian is “of a different faith” from Catholic Christianity. We are all believers in Jesus and we share one Christian faith, although, in the household described above, there are a great variety of theological ideas and disciplinary concerns.

Officially, “ecclesial communities” is the Catholic term for referring to Christian bodies lacking valid ordination and hence lacking a valid sacrament of the Holy Eucharist. We Catholics recognize apostolic succession, and thus valid ordination and Eucharist, in the Eastern and Oriental Orthodox Churches and in some other, relatively small, religious bodies. You and I have much more contact with Christians called “Protestants” (a convenient term which nevertheless lacks nuance in telling the story of how individual groups came to be). Obviously, between Catholics and most non-Catholic Christians whom we know, issues of ordination and Eucharist are major challenges to achieving Christian unity around a common eucharistic table. Most non-Catholic Christian groups refer to themselves as “churches,” and of course we respect the right of individuals and groups to name themselves.

So, ecumenical activity seeks to bring the unity intended by Jesus into the household of Christianity. It is easy — indeed almost a reflex — to focus on the differences between Christian groups. We must address the issues which divide us. But our starting point must be in understanding and appreciating what Christians share. And of course we share Jesus. All of us, in an ecumenical context or not, can benefit from exploring the mystery of the Son of God, the Word Made Flesh.

Interreligious activity is quite different from our ecumenical explorations. The interreligious adventure challenges Christians to appreciate what we share with non-Christians. One may ask whether we share anything with them. The answer is that we do. We Christians hold — and we cannot compromise on this — that Jesus is the unique savior of humanity. We find, in our interreligious dialogues, that even the concept of “salvation” is a matter for clarification, as are matters of a human relationship with a God or gods. In interreligious conversation, we do not seek to impose Christian beliefs upon non-Christians. Our talking about our own religious experience must always be accompanied by generous listening. When learning about Hinduism, Buddhism, Judaism, and Islam, we must keep in mind the many centuries of history and human experience behind these various beliefs.

This is a sweeping overview of the fascinating terrain of religious thought, belief, and practice. The reader can, of course, look forward to discussions in which we examine the terrain more slowly. God is calling each of us to look at the religious situation we find ourselves in, to consider the marvels of human thought about the ultimate realities, and to appropriate to ourselves, with ever greater conviction, an appreciation of the faith we profess.