In both East and West, the dates of many feasts vary from year to year, usually in line with the variation in the date of Easter, with which most other moveable feasts are associated. The extent to which feasts and festivals are celebrated also varies between churches; in general, Protestant churches observe far fewer than Catholic and Orthodox, in particular with regard to feasts of the Virgin Mary and the other Saints.

Liturgical cycle

The liturgical cycle divides the year into a series of seasons, each with their own mood, theological emphases, and modes of prayer, which can be signified by different ways of decorating churches, colors of Paraments and Vestments for clergy, scriptural readings, themes for preaching and even different traditions and practices often observed personally or in the home. In churches that follow the liturgical year, the scripture passages for each Sunday (and even each day of the year in some traditions) are specified by a list called a lectionary.

Among non-Catholic Western Christians, Anglicans and Lutherans have traditionally followed the lectionary since the days of the Protestant Reformation. Following the Roman Catholic liturgical reform of the Roman Rite instituted by Pope Paul VI in 1969, the adoption and use of lectionaries in other Protestant churches (Methodist, Reformed, United, etc.) increased. In particular, the growing influence of the Revised Common Lectionary led to a greater awareness of the Christian year among Protestants in the later decades of the 20th century, especially among mainline denominations.

Biblical calendar

Biblical calendars are lunisolar calendars based on the cycle of the new moon, in its original meaning of the first visible crescent. The year is from the first new moon on or after the spring equinox to the next new moon on or after the spring equinox, which means its starting point is different from the modern Western calendar (which is a solar calendar adjusted with leap years and leap seconds to keep it in sync with the solar year). The basic formula for the bibical calendar is found early in the Bible: "And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years" (Gen. 1:14). "This month shall be unto you the beginning of months: it shall be the first month of the year to you" (Exo. 12:1-2). "This day came ye out in the month Abib" (Exo. 13:4). A month is one new moon to the next new moon. "And it shall come to pass, that from one new moon to another (month), and from one Sabbath to another, shall all flesh come to worship before me, said the LORD" (Isa. 66:23). "In the first month, that is, the month Nisan, in the twelfth year of king Ahasuerus, they cast Pur, that is, the lot, before Haman from day to day, and from month to month, to the twelfth month, that is, the month Adar" (Est. 3:7). The Biblical Calendar is laid out as follows, Nisan or Nissan (1st month) March-April, Iyar (2nd month) April-May, Sivan (3rd month) May-June, Tammuz (4th month) June-July, Av (5 month) July-August, Elul (6 month) August-September, Tishrei (7th month) September-October, Heshvan or Cheshvan (8th month) October-November, Kislev (9th month) November-December, Tevet (10th month) December-January, Shevat (11th month) January-February, Adar (12th month) February-March.

Western liturgical calendar

Western Christian liturgical calendars are based on the cycle of the Roman Rite of the Catholic Church, including Lutheran, Anglican, and other Protestant calendars since this cycle pre-dates the Reformation. Generally, the liturgical seasons in western Christianity are Advent, Christmas, Ordinary Time (Time after Epiphany), Lent, Easter, and Ordinary Time (Time after Pentecost).

Catholic Church liturgical year

The Catholic Church sets aside certain days and seasons of each year to recall and celebrate various events in the life of Christ. In its Roman Rite the liturgical year begins with Advent, the time of preparation for both the celebration of Jesus' birth, and his expected second coming at the end of time. This season lasts until 24 December (Christmas Eve). Christmastide follows, beginning with First Vespers of Christmas on the evening of 24 December and ending with the feast of the Baptism of Jesus. Lent is the period of purification and penance which begins on Ash Wednesday and ends on Holy Thursday. The Holy Thursday evening Mass of the Lord's Supper marks the beginning of the Easter Triduum, which includes Good Friday, Holy Saturday, and Easter Sunday. These days recall Jesus' Last Supper with his disciples, death on the cross, burial, and resurrection. The seven-week liturgical season of Easter immediately follows the Triduum, climaxing at Pentecost. This last feast recalls the descent of the Holy Spirit upon Jesus' disciples after the Ascension of Jesus. The rest of the liturgical year is commonly known as Ordinary Time.^[1]

There are many forms of liturgy in the Catholic Church. Even putting aside the many Eastern rites in use, the Latin liturgical rites alone include the Ambrosian Rite, the Mozarabic Rite, and the Cistercian Rite, as well as other forms that have been largely abandoned in favour of adopting the Roman Rite. Of this rite, what is now the "ordinary" or, to use a word employed in the Letter of Pope Benedict XVI accompanying the motu proprio Summorum Pontificum, the "normal" form is that which developed from the Second Vatican Council to the present day, while the form in force in 1962 is authorized as an extraordinary form of the Roman Rite without restriction in private celebrations and under certain conditions in public celebrations. The liturgical calendar in that form of the Roman Rite (see General Roman Calendar of 1962) differs in some respects from that of the present ordinary form, as will be noted below, and also from the earlier General Roman Calendar of Pope Pius XII, the still earlier General Roman Calendar of 1954 and the original Tridentine Calendar. These articles can be consulted with regard to the Roman-Rite liturgical year before 1962.

Advent

From the Latin adventus, "arrival" or "coming", the first season of the liturgical year begins four Sundays before Christmas and ends on Christmas Eve. Traditionally observed as a "fast", its purpose focuses on preparation for the coming of Christ. Although often conceived as awaiting the coming of the Christ-child at Christmas, the modern Lectionary points the season more toward eschatological themes—awaiting the final coming of Christ, when "the wolf shall live with the lamb" (Isaiah 11:6) and when God will have "brought down the powerful from their thrones, and lifted up the lowly" (The Magnificat, Luke 1:52)—particularly in the earlier half of the season. This period of waiting is often marked by the Advent Wreath, a garland of evergreens with four candles. Although the main symbolism of the advent wreath is simply marking the progression of time, many churches attach themes to each candle, most often 'hope', 'faith', 'joy', and 'love'.

Color: Violet, but on the third Sunday of Advent, Gaudete Sunday, Rose may be used instead.

During this season, the Roman Catholic Church typically omits the "Gloria in Excelsis" during Mass, but retains it for the Mass celebrating a feast. The word "Alleluia" is not banned, as in Lent, but the 1962 form of the Roman Rite a Gradual is used instead of an Alleluia and verse, except on Sunday.

Christmas

The Christmas season immediately follows Advent. The traditional Twelve Days of Christmas begin with Christmas Eve on the evening of December 24 and continue until the feast of Epiphany. The actual Christmas season continues until the Feast of the Baptism of Christ, which in the present form of the Roman Rite is celebrated on the Sunday after 6 January. In the 1962 form, this feast is celebrated on 13 January, unless 13 January is a Sunday, in which case the feast of the Holy Family is celebrated instead.^[2] Until the suppression of the Octave of the Epiphany in the 1960 reforms, 13 January was the Octave day of the Epiphany, providing the date for the end of the season.

Color: White or Gold.

Ordinary Time or Time after Epiphany

"Ordinary" comes from the same root as our word "ordinal", and in this sense means "the counted weeks". In the Roman Catholic Church and in some Protestant traditions, these are the common weeks which do not belong to a proper season. In Latin, these seasons are called the weeks per annum, or "through the year".

In the current form of the Roman Rite adopted following the Second Vatican Council, Ordinary Time consists of 33 or 34 Sundays and is divided into two sections. The first portion extends from the day following the Feast of the Baptism of Christ until the day before Ash Wednesday (the beginning of Lent). It contains anywhere from three to eight Sundays, depending on how early or late Easter falls. The main focus in the readings of the Mass is Christ's earthly ministry, rather than any one particular event. The counting of the Sundays resumes following Eastertide, however, two Sundays are replaced by Pentecost and Trinity Sunday, and depending on whether the year has 52 or 53 weeks, one may be omitted.

In the 1962 form of the Roman Rite, the Time after Epiphany has anywhere from one to six Sundays. As in the current form of the rite, the season mainly concerns Christ's preaching and ministry, with many of his parables read as the Gospel readings. The season begins on 14 January^[3] and ends on the Saturday before Septuagesima Sunday. Omitted Sundays after Epiphany are transferred to Time after Pentecost and celebrated between the Twenty-Third and the Last Sunday after Pentecost according to an order indicated in the Code of Rubrics, 18, which also states that, if there are not enough Sundays in the year to accommodate them all, then those for which there is no room are omitted.

Color: Green

Septuagesima

Until the 1969 reform of the Roman Missal and General Calendar, the two-and-a-half-week period before Lent formed a pre-Lenten season called Septuagesima, the Latin word for "seventieth". The season of Septuagesima thus remains in the 1962 form of the Roman rite as well as in some Protestant calendars. It is a transition from the first part of the season per annum^[4] to the season of Lent, and a preparation for the fasting and penance which begin on Ash Wednesday. Although most of the Divine Office remains the same as during the season per annum, certain customs of Lent are adopted, including the suppression of the "Alleluia", the replacement of the Alleluia at Mass with the Tract and the Gloria is no longer said on Sundays.

In the post-1969 form of the Roman Rite, there is no intermediary season between Ordinary Time and Lent.

Color: Violet

Lent and Passiontide

Lent is a major penitential season of preparation for Easter. It begins on Ash Wednesday and, if the penitential days of Good Friday and Holy Saturday are included, lasts for forty days, since the six Sundays within the season are not counted.

In the Roman Rite the Gloria in Excelsis Deo and the Te Deum are not used in the Mass and Liturgy of the Hours respectively, except on Solemnities and Feasts, and the Alleluia and verse that usually precede the reading of the Gospel is either omitted or replaced with another acclamation.

Lutheran churches make these same omissions.

As in Advent, the deacon and subdeacon of the 1962 form of the Roman Rite do not wear their habitual dalmatic and tunicle (signs of joy) in Masses of the season during Lent; instead they wear "folded chasubles", in accordance with the ancient custom.

In the 1962 form of the Roman Rite, the last two Sundays in the season of Lent are called the First and Second Sundays in Passiontide, and in all Masses of the last two weeks the Gloria Patri is omitted at the Entrance Antiphon.^[5] The veiling of crucifixes and images of the saints with violet cloth, which was obligatory in 1962 is left to the decision of the national bishops conference in the later form of the Roman Rite. In all forms, the readings begin to focus even more on the Passion of Christ.

The last week of Lent is called Holy Week.

In the Roman Rite, feasts that fall within that week are simply omitted, unless they have the rank of Solemnity, in which case they are transferred to another date. The only solemnities inscribed in the General Calendar that can fall within that week are those of St. Joseph and the Annunciation.

Color: violet. In some traditions, rose may be used on the 4th Sunday of Lent, called Laetare Sunday in the Roman Rite. Red is used for Palm Sunday in this rite (but only for the blessing of the palms in its 1962 form). In the traditional form of the Palm Sunday liturgy, before the reforms of 1955, violet was used in the Roman rite both for the blessing of palms and procession and for the subsequent Mass.

Easter Triduum

The Easter Triduum consists of Good Friday, Holy Saturday and Easter Sunday.^[6]

It begins on the evening before Good Friday with Mass of the Lord's Supper, celebrated with white vestments,^[7] which often includes a ritual of ceremonial footwashing. In other traditions also a footwashing ritual is observed. It is customary on this night for a vigil involving private prayer to take place, beginning after the evening service and continuing until midnight. This vigil is occasionally renewed at dawn, continuing until the Good Friday liturgy.

During the day of Good Friday Mass is not celebrated in the Catholic Church. Instead a Celebration of the Passion of the Lord is held in the afternoon or evening. It consists of three parts: a Liturgy of the Word that includes the reading of the account of the Passion by John the Evangelist and concludes with a solemn Universal Prayer. Other churches also have their Good Friday commemoration of the Passion. The color of vestments varies: no color, red, or black are used in different traditions. Colored hangings may be removed. Lutheran churches often either remove colorful adornments and icons, or veil them with drab cloth. The service is usually plain with somber music, ending with the congregation leaving in silence. In the Roman Catholic, some Lutheran, and High Anglican rites, a crucifix (not necessarily the one which stands on or near the altar on other days of the year) is ceremoniously unveiled. Other crucifixes are unveiled, without ceremony, after the service.

Holy Saturday commemorates the day during which Christ lay in the tomb. In the Roman Catholic Church, there is no Mass on this day; the Easter Vigil Mass, which, though celebrated properly at the following midnight, is often celebrated in the evening, is an Easter Mass. With no liturgical celebration, there is no question of a liturgical color.

The Easter Vigil is held in the night between Holy Saturday and Easter Sunday, to celebrate the resurrection of Jesus. See also Paschal candle. The liturgical color is white, often together with gold. In the Roman Rite, during the "Gloria in Excelsis Deo" the organ and bells are used in the liturgy for the first time in 2 days, and the statues, which have been veiled during Passiontide, are unveiled. In Lutheran churches, colors and icons are re-displayed as well