"Holy Father, keep them in your name that you have given me,
so that they may be one, just as we are."
Gospel of John 17:11
"May the God of endurance and encouragement grant you to think in harmony with one another, in keeping with Christ Jesus,
that with one accord you may with one voice glorify the God and Father of our Lord Jesus Christ."
Epistle of St. Paul to the Romans 15:5-6
"I urge you, brothers, in the name of our Lord Jesus Christ, that all of you agree in what you say,
and that there be no divisions among you, but that you be united in the same mind and in the same purpose."
First Letter of St. Paul to the Corinthians 1:10
"I, then, a prisoner for the Lord, urge you to live in a manner worthy of the call you have received,
with all humility and gentleness, with patience, bearing with one another through love, a striving to preserve the unity
of the spirit through the bond of peace: one body and one Spirit, as you were also called to the one hope of your call;
one Lord, one faith, one baptism; one God and Father of all, who is over all and through all and in all."
Letter of St. Paul to the Ephesians 4:1-5
The third Millennium is a time to restore Christian unity, as in the times of Jesus. Christian unity was the prayer of Jesus (John 17:11 and 17:21) and the plea of St. Paul, the Apostle to the Gentiles, throughout his Epistles.
History has recorded divisions within the Church of Jesus Christ. The teaching of the Council of Ephesus in 431 (on Mary as Mother of God) was not accepted by the independent Church of the East in Persia.2 Those Eastern Churches that believed that Jesus was one incarnate nature of the Word of God formed the Oriental Orthodox Churches, for they did not accept the teaching of the Council of Chalcedon in 451, that Jesus was one Person with two natures, Divine and human in perfect harmony. A major split occurred during the Schism of 1054 between the Byzantine Orthodox of Constantinople and the Catholic Church of Rome.3 The Protestant Reformation that began with Martin Luther in 1517 constituted the major division in the West.4
This lack of Christian unity proved to be a grave impediment to bringing non-Christians into the Church. The loss of Christian unity led to the secularization of Western culture. Recognition of this problem served as an impetus toward Christian unity among the Protestants in the early twentieth century, beginning with the World Missionary Conference of Edinburgh in 1910, and the formal organization of the World Council of Churches in 1948.5 The call for Christian unity accelerated with the surprise announcement of Pope John XXIII for the Second Vatican Council on January 25, 1959.6 The Council was pastoral in nature and was held from 1962-1965.7 Pope John Paul II made great efforts to continue the ecumenical movement throughout his Papacy.8
The call for Christian unity in the twentieth century was a watershed event for Christian Churches, and could not have been more timely. While Christians have fought among themselves for centuries over theological differences, secular humanism and materialism have swept the globe, and threaten to eradicate religion itself, especially among the young. This is a time we Christians must be united in our spread of the Gospel of Jesus Christ in the face of secularism and atheism.
Christian unity will be achieved when all believers open their hearts to Christ Jesus and to each other.
"Is not the cup of blessing which we bless a sharing in the blood of Christ?
Is not the bread which we break a sharing in the body of Christ?
Since there is one bread, we who are many are one body;
for we all partake of the one bread.
First Letter of St. Paul to the Corinthians 10:16-17
"Mend your ways, encourage one another, live in harmony,
and the God of love and peace will be with you all.
Second Letter of Paul to the Corinthians 13:11
"Only conduct yourselves in a way worthy of the gospel of Christ, so that,
whether I come and see you or am absent, I may hear news of you, that you are standing firm in one spirit,
with one mind struggling together for the faith of the gospel."
Letter of St. Paul to the Philippians 1:27
1 The Navarre Revised Standard Version of the Holy Bible. Four Courts Press, Dublin, Ireland, 1999-2005.
2 Christopher Dawson.The Formation of Christendom. (New York: Sheed and Ward, 1967), 116-153.
3 Bishop Timothy Ware. "The Reunion of Christians," in The Orthodox Church, Third Edition. (London: Penguin, 2015), 300-319.
4 William C. Placher & Derek R. Nelson. A History of Christian Theology, Second Edition. (Louisville, Kentucky: John Knox Press, 2013), 153-169.
5 Jackson J. Spielvogel. Western Civilization. Sixth Combined Edition, Thomson Wadsworth, Belmont, California, 346-376, 2006.
6 Pope John XXIII. Announcement of Second Vatican Council, January 25, 1959. Vatican II Council Daybook, Volume 1, Session 1, October 11 - December 8, 1962. National Catholic Welfare Conference, Washington, D. C., 1-2, 1965.
7 Douglas Bushman (ed): The Sixteen Documents of Vatican II. Pauline Books and Media, Boston, 1999.
8 Pope John Paul II. That All May Be One, the encyclical Ut Unum Sint. Pauline Books & Media, Boston, March 25, 1995.