Feast of Christ the King

The Solemnity of Our Lord Jesus Christ, King of the Universe, commonly referred to as the Feast of Christ the King, Christ the King Sunday of Reign of Christ Sunday, is a relatively recent addition to the Western liturgical calendar, having been instituted in 1925 by Pope Pius XI for the Roman Rite of the Catholic Church. In 1970 its Roman Rite observance was moved to the final Sunday of Ordinary Time. Therefore, the earliest date on which it can occur is 20 November and the latest is 26 November. The Lutheran, Anglican, Moravian, Methodist, Reformed and United Protestant churches also celebrate the Feast of Christ the King, which is contained in the Revised Common Lectionary; the Methodist, Anglican and Presbyterian Churches historically observed this as part of the liturgical season of Kingdomtide, which runs between Trinity Sunday and the Feast of Christ the King. Roman Catholics adhering to the Extraordinary Form of the Roman Rite use the General Roman Calendar of 1960, and as such continue to observe the Solemnity on its original date of the final Sunday of October. It is also observed on the same computed date as the final Sunday of the ecclesiastical year, the Sunday before the First Sunday of Advent, by Western-rite parishes of the Russian Orthodox Church Outside Russia.
Origin in patristics.
According to Cyril of Alexandria, "Christ has dominion over all creatures, ...by essence and by nature." His kingship is founded upon the hypostatic union. "[T]he Word of God, as consubstantial with the Father, has all things in common with him, and therefore has necessarily supreme and absolute dominion over all things created."
"From this it follows that to Christ angels and men are subject. Christ is also King by acquired, as well as by natural right, for he is our Redeemer. ...' We are no longer our own property, for Christ has purchased us "with a great price"; our very bodies are the "members of Christ." A third ground of sovereignty is that God bestowed upon Christ the nations of the world as His special possession and dominion. "All power in heaven and on earth has been given to me." (Matthew 28:18)
The Feast of Christ the King has an eschatological dimension pointing to the end of time when the kingdom of Jesus will be established in all its fullness to the ends of the earth. It leads into Advent, when the Church anticipates Christ’s second coming.
Observance.
Roman Catholic Church.
Pope Pius XI instituted the Feast of Christ the King in his encyclical "Quas primas" of 1925, in response to growing secularism and nationalism, and in the context of the unresolved Roman Question.
The title of the feast was "Domini Nostri Jesu Christi Regis" ([of] Our Lord Jesus Christ the King), and the date was established as "the last Sunday of the month of October – the Sunday, that is, which immediately precedes the Feast of All Saints". In Pope John XXIII's revision of the calendar in 1960, the date and title were unchanged but, according to the simplification of the ranking of feasts, it was classified as a feast of the first class. 
In his "motu proprio" "Mysterii Paschalis" of 1969, Pope Paul VI amended the title of the Feast to "D. N. Iesu Christi universorum Regis" (Our Lord Jesus Christ King of the Universe). He also moved it to the new date of the final Sunday of the liturgical year, before the commencement of a new liturgical year on the First Sunday of Advent (the earliest date for which is 27 November). Through this choice of date "the eschatological importance of this Sunday is made clearer". He assigned to it the highest rank of "solemnity".
In , the Solemnity day falls on . The liturgical vestments for the day are colored white or gold, in keeping with other joyous feasts honoring Christ.
In the extraordinary form, as happens with all Sundays whose liturgies are replaced by those of important feasts, the prayers of the Sunday on which the celebration of the feast of Christ the King occurs are used on the ferias (weekdays) of the following week. The Sunday liturgy is thus not totally omitted. In , the Solemnity day falls on for those using the former calendar.
Moravian Church.
In the Moravian Church, Reign of Christ Sunday is the feast marking the end of Pentecostide. Red is the liturgical colour associated with the Reign of Christ.
Lutheran Churches.
In the Evangelical-Lutheran Church of Sweden and the Church of Finland, this day is referred to as Judgement Sunday, previously highlighting the final judgement, though after the Swedish Lectionary of 1983 the theme of the day was amended to the "Return of Christ". A distinct season of Kingdomtide is or has been observed by a number of churches on the four Sundays before Advent, either officially or semi-officially. 
Anglican Churches.
At the Church of England, the "annual cycle of the Church’s year now ends".
In the Church in Wales, part of the Anglican Communion, these four Sundays before Advent are called the "Sundays of the Kingdom" and Christ the King is observed as a season and not as a single festal day.
Reformed Churches.
The Continental Reformed Churches, such as the Christian Reformed Churches, assign the following hymns to be used on the Feast of Christ the King: "Crown Him with Many Crowns", "Lo! He comes with clouds descending", and "Rejoice, the Lord Is King".
In the Presbyterian Churches, such as the Presbyterian Church (USA), at the Feast of Christ the King (Feast of the Reign of Christ) "the church gives thanks and praise for sovereignty of Christ, who is Lord of all creation and is coming again in glory to reign (see Revelation 1:4-8)."
In the United Church of Christ, a Congregationalist denomination, the Feast of Christ the King is the last Sunday of the liturgical season known as the Time of the Church.
Methodist Churches.
The Feast of Christ the King is observed in the Methodist Churches, such as the United Methodist Church, as the last Sunday of the liturgical season of Kingdomtide. The season of Kingdtomtide itself starts on Trinity Sunday and culminates in the Feast of Christ the King. Methodist parishes have been dedicated to Christ the King.
United Protestant Churches.
In United Protestant Churches, such as the United Church of Canada, Uniting Church of Australia, Church of North India, Church of Pakistan and Church of South India, the Feast of Christ the King (Reign of Christ), is observed as the last Lord's Day of the liturgical kalendar.
Significance for the laity.
While the encyclical that established this feast was addressed, according to the custom of the time, to the Catholic Bishops, Pope Pius XI wanted the Feast to impact the laity:
"If to Christ our Lord is given all power in heaven and on earth; if all men, purchased by his precious blood, are by a new right subjected to his dominion; if this power embraces all men, it must be clear that not one of our faculties is exempt from his empire. He must reign in our minds, which should assent with perfect submission and firm belief to revealed truths and to the doctrines of Christ. He must reign in our wills, which should obey the laws and precepts of God. He must reign in our hearts, which should spurn natural desires and love God above all things, and cleave to him alone. He must reign in our bodies and in our members, which should serve as instruments for the interior sanctification of our souls, or to use the words of the Apostle Paul, as instruments of justice unto God."