Which denominations have official flags?

Flag of the Greek Orthodox Church

The Ecumenical Patriarchate and Mount Athos, and also the Greek Orthodox Churches in the diaspora under the Patriarchate use a black double-headed eagle in a yellow field as their flag or emblem.

The eagle is depicted as clutching a sword and an orb with a crown above and between its two heads. An earlier variant of the flag, used in the 1980s, combined the double-headed eagle design with the blue-and-white stripes of the flag of Greece.

The design is sometimes dubbed the "Byzantine imperial flag", and is considered—inaccurately—to have been the actual historical banner of the Byzantine Empire. The double-headed eagle was historically used as an emblem in the late Byzantine period (14th–15th centuries), but not on flags; rather it was embroidered on imperial clothing and accoutrements by both the Palaiologos emperors of the Byzantine Empire and the Grand Komnenos rulers of the Empire of Trebizond, descendants of the Byzantine imperial family of the same name. The actual flag of the Palaiologan-era Byzantine Empire was based on the tetragrammatic cross in gold on a red background. This design also forms the basis for another flag used by the Orthodox Church of Greece, with the added inscription of TOYTῼ NIKA (i.e. in hoc signo vinces).

Episcopal Church Flag

On Oct. 16, 1940, the House of Bishops and the House of Deputies adopted an official flag for the Episcopal Church. This was the 251st anniversary of the day the General Convention ratified the Constitution and Canons and adopted the BCP. It was designed by William M. Baldwin (d. 1942), a member of the Cathedral of the Incarnation, Long Island, New York. The symbolism of the flag has been explained as follows: The white field represents the purity of the Christian religion. The red cross represents the sacrifice of Jesus and the blood of the martyrs. The red cross on a white field is the cross of Saint George, the patron saint of England, indicating our descent from the Church of England. The blue in the upper left-hand corner is the light blue of the sky, often used by artists for the clothing of the Blessed Virgin. It is called Madonna blue and represents the human nature of our Lord, which he received from his mother. The nine white crosslets on the blue field represent the nine original dioceses of the Episcopal Church in America in 1789: Massachusetts, Connecticut, New York, New Jersey, Pennsylvania, Maryland, Virginia, Delaware, and South Carolina. They are arranged in the form of a St. Andrew's Cross to commemorate the fact that Samuel Seabury, the first American bishop, was consecrated in Aberdeen, Scotland, on Nov. 14, 1784. The colors red, white, and blue represent the United States and stand for the American branch of the Anglican Communion. The same design is incorporated in the Episcopal Church seal, which was also adopted by the 1940 General Convention. The seal and flag serve as emblems of the Episcopal Church. The design is seen on signs, publications, decals, letterheads, pins, and many other places. Some congregations display the Episcopal Church flag and the American flag in the church or parish hall.

Christian Flag

The Christian Flag is an ecumenical flag designed in the early 20th century to represent much of Christianity and Christendom. Since its adoption by the United States Federal Council of Churches in 1942, it has been used by congregations of many Christian traditions, including Anglican, Baptist, Congregationalist, Lutheran, Mennonite, Methodist, Moravian, Presbyterian, and Reformed, among others.

The flag has a white field, with a red Latin cross inside a blue canton. The shade of red on the cross symbolizes the blood that Jesus shed on Calvary. The blue represents the waters of baptism as well as the faithfulness of Jesus. The white represents Jesus' purity. The dimensions of the flag and canton have no official specifications.

The ecumenical organization, Federal Council of Churches (now succeeded by the National Council of Churches and Christian Churches Together) adopted the flag on 23 January 1942, 45 years after unofficial use since 1897; the Federal Council of Churches represented Baptist, Brethren, Eastern Orthodox, Episcopal, Methodist, Moravian, Lutheran, Oriental Orthodox, Polish National Catholic, Presbyterian, Quaker, and Reformed traditions, among others. The Christian Flag intentionally has had no copyright or trademark rights connected to it, as the designer freely dedicated the flag to all of Christendom. Fanny Crosby wrote the words to a hymn called "The Christian Flag" with music by R. Huntington Woodman. Like the flag, the hymn is free use. On the Sunday nearest 26 September 1997, the Christian Flag celebrated its one hundredth anniversary.

Mainline Protestant denominations in the United States accepted the flag first, and by the 1980s many institutions had described policies for displaying it inside churches. The Federal Council of Churches recommended that if the Christian Flag is to be used alongside a national flag, that the Christian Flag should receive the place of honour. During World War II the flag was flown along with the U.S. flag in a number of Lutheran churches, many of them with German backgrounds, who wanted to show their solidarity with the United States during the war against Nazi Germany.

The Christian Flag!