Orthodox Churches may seem strange and unfamiliar to Catholics, but Catholicism and Orthodoxy actually are closely connected in terms of faith, the sacraments and Church governance. In fact, the two are often described as “sister Churches.”

Orthodoxy and Catholicism are so similar that Pope John Paul II issued an apostolic letter three years ago in which he said it would be scandalous if a commitment to full unity was not made. That same year he hosted the Orthodox patriarch of Constantinople at the Vatican.

The Orthodox are a major presence in the United States with about five million members. The 14 or 15 Eastern Orthodox Churches (the status of one is not accepted by all) are separated by nationality or language but share the same faith. The Greek Orthodox Church and the Serbian Orthodox Church are two of the most prominent.

Catholicism and Orthodoxy share many characteristics:

3 Both are sacramental Churches. Like Catholics, Orthodox participate in seven sacraments. An Orthodox can become a Catholic by simply making a profession of faith. A Catholic, if a priest is unavailable, is allowed to receive some sacraments from an Orthodox priest.

3 The Churches share common ground on faith and morals.

3 Despite some differences, the Mass and the Orthodox liturgy have much in common. The latter is structured like the Mass. Like Catholics, Orthodox believe the Eucharist is the real presence of Jesus.

3 Both treasure a great devotion to Mary.

3 Both greatly value monastic life.

A major difference between the two faiths is that the Orthodox Church ordains married men. But most observers agree that the chief obstacle to union remains the role of the Pope. The Orthodox Churches are headed by patriarchs, who are seen as “first among equals.”

— Jay Copp