In countries which use the Gregorian calendar, New Year's Day is usually celebrated on 1 January. The order of months in the Roman calendar has been January to December since King Numa Pompilius in about 700 BC, according to Plutarch and Macrobius. However, Roman writers identified years by naming the year's consuls, who did not enter office on 1 January until 153 BC. Since then 1 January has been the first day of the year, except during the Middle Ages when several other days were the first (1 March, 25 March, Easter, 1 September, 25 December). With the expansion of Western culture to the rest of the world during the twentieth century, the 1 January date became global, even in countries with their own New Year celebrations on other days (e.g., China and India). At present, the celebration of the New Year is a major event worldwide. Many large-scale events are held in major cities around the world, with many large fireworks events on New Year's Eve (31 December). Sydney launched over 80,000 fireworks at midnight, and had more than one and a half million attendees; it was also the most-watched event on television worldwide last year. In Valparaiso upwards of two million visitors witnessed the largest fireworks display in a natural setting; a total of more than 21 kilometers of fireworks on the bay, from the commercial port city of Valparaiso to Concon, Chile, all in 25 minutes of entertainment. London's New Year celebrations centre around the London Eye, with an impressive fireworks display while Big Ben strikes midnight. In New York, the celebration is focused around a large crystal ball that descends in a one minute countdown in Times Square. Edinburgh plays host to one of the world's largest Hogmanay events. The celebrations last for four days and attract visitors from around the globe to take part in street parties and attend concerts. In the culture of Latin America there are a variety of traditions and superstitions surrounding these dates as omens for the coming year. January remains a symbol of the New Year's celebration. According to the Christian tradition, 1 January coincides with the circumcision of Christ (eight days after birth), when the name of Jesus was given to him (Luke 2: 21).

Epiphany (from Koine Greek (ἡ) ἐπιφάνεια, epiphaneia "appearance", "manifestation") is a Christian feast day that celebrates the revelation of God made Man in the person of Jesus Christ. It falls on 6 January or, in many countries, on the Sunday that falls between 2 January and 8 January. Since the Julian Calendar, which is followed by some Eastern Churches, is at present 13 days behind the Gregorian Calendar and the revised Julian Calendar, 6 January in that calendar corresponds at present to 19 January in what is the official civil calendar in most countries. On this feast, Western Christians commemorate principally the visitation of the Biblical Magi to the Baby Jesus, i.e., his manifestation to the Gentiles; Eastern Christians commemorate the baptism of Jesus in the Jordan River, seen as his manifestation to the world as the Son of God. It is also called Theophany, especially by Eastern Christians.

Eid al-Adha (Arabic: عيد الأضحى‎ ‘Īdu l-’Aḍḥā) "Festival of Sacrifice" or "Greater Eid" is an important religious holiday celebrated by Muslims worldwide to commemorate the willingness of Abraham (Ibrahim) to sacrifice his son as an act of obedience to God, but instead was able to sacrifice a ram (by God's command). Eid is also about spending time with family and friends, sacrifice, and thanksgiving for being able to afford food and housing. In traditional or agrarian settings, each family would sacrifice a domestic animal, such as a sheep, goat, cow, or camel, by slaughter (though many contemporary muslims do not sacrifice an animal as part of their observance). The meat would then be divided into three equal parts to be distributed to others. The family eats one third, another third is given to other relatives, friends or neighbors, and the other third is given to the poor as a gift. Eid al-Adha is the latter of two Eid festivals celebrated by Muslims, whose basis comes from the Quran. Like Eid ul-Fitr, Eid al-Adha begins with a short prayer followed by a sermon (khuṭba). Eid al-Adha is celebrated annually on the 10th day of the month of Dhul Hijja (ذو الحجة) of the lunar Islamic calendar. The festivities last for three days or more depending on the country. Eid al-Adha celebrations start after the Hajj, the annual pilgrimage to Mecca in Saudi Arabia by Muslims worldwide, descend from Mount Arafat. The date is approximately 70 days after the end of the month of Ramadan.

Saint Joseph's Day, March 19, the Feast of St. Joseph or Solemnity of Saint Joseph is in Western Christianity the principal feast day of Saint Joseph, Spouse of the Blessed Virgin Mary.[1] It is a Solemnity in the Roman Catholic Church, and also a feast in the provinces of the Anglican Communion, and a feast or festival in the Lutheran Church. Saint Joseph's Day is the Patronal Feast day for persons named Joseph, Josephine, etc., for religious orders, schools and parishes bearing his name, and for carpenters. It is also Father's Day in some Catholic countries, mainly Spain, Portugal, and Italy.

Good Friday, also called Holy Friday, Black Friday, or Great Friday, is a holiday observed primarily by adherents to Christianity commemorating the crucifixion of Jesus and his death at Calvary. The holiday is observed during Holy Week as part of the Paschal Triduum on the Friday preceding Easter Sunday, and often coincides with the Jewish observance of Passover. Based on the scriptural details of the Sanhedrin Trial of Jesus, the Crucifixion of Jesus was most probably on a Friday. The estimated year of Good Friday is AD 33, by two different groups, and originally as AD 34 by Isaac Newton via the differences between the Biblical and Julian calendars and the crescent of the moon. A third method, using a completely different astronomical approach based on a lunar Crucifixion darkness and eclipse model (consistent with Apostle Peter's reference to a "moon of blood" in Acts 2:20) arrives at the same date, namely Friday April 3, AD 33.

Easter (Greek: Πάσχα) is the most important annual religious feast in the Christian liturgical year. According to Christian scripture, Jesus was resurrected from the dead on the third day of his crucifixion. Christians celebrate this resurrection on Easter Day or Easter Sunday (also Resurrection Day or Resurrection Sunday), two days after Good Friday and three days after Maundy Thursday. The chronology of his death and resurrection is variously interpreted to be between AD 26 and AD 36. Easter also refers to the season of the church year called Eastertide or the Easter Season. Traditionally the Easter Season lasted for the forty days from Easter Day until Ascension Day but now officially lasts for the fifty days until Pentecost. The first week of the Easter Season is known as Easter Week or the Octave of Easter. Easter also marks the end of Lent, a season of fasting, prayer, and penance. Easter is a moveable feast, meaning it is not fixed in relation to the civil calendar. The First Council of Nicaea (325) established the date of Easter as the first Sunday after the full moon (the Paschal Full Moon) following the vernal equinox. Ecclesiastically, the equinox is reckoned to be on March 21. The date of Easter therefore varies between March 22 and April 25. Eastern Christianity bases its calculations on the Julian Calendar whose March 21 corresponds, during the twenty-first century, to April 3 in the Gregorian Calendar, in which calendar their celebration of Easter therefore varies between April 4 and May 8. Easter is linked to the Jewish Passover not only for much of its symbolism but also for its position in the calendar. Relatively newer elements such as the Easter Bunny and Easter egg hunts have become part of the holiday's modern celebrations, and those aspects are often celebrated by many Christians and non-Christians alike.

International Workers' Day (a name used interchangeably with may day) is a celebration of the social and economic achievements of the international labor movement. May Day commonly sees organized street demonstrations and street marches by millions of working people and their labour unions throughout most of the countries of the world.

The Christian doctrine of the Ascension holds that Jesus ascended to heaven in the presence of his Eleven Apostles following his resurrection, and that in heaven he sits at the right hand of God the Father. Jesus died circa 30. In the Epistle to the Romans (c. 56-57), Saint Paul describes Christ as in heaven and in the abyss[Rom. 10:5-7] the earliest Christian reference to Jesus in heaven. The most influential account of the Ascension, and according to the two-source hypothesis the earliest, is in Acts of the Apostles[1:1-11] where Jesus is taken up bodily into heaven forty days after his resurrection as witnessed by his apostles, after giving the Great Commission with a prophecy to return. In the Gospel of Luke, the Ascension takes place on Easter Sunday evening. The Gospel of John (c. 90-100) refers to Jesus returning to the Father.[Jn. 20:17] In the First Epistle of Peter (c. 90-110), Jesus has ascended to heaven and is at God's right side. Pet. 3:21-22] The Epistle to the Ephesians (c. 90-100) refers to Jesus ascending higher than all the heavens.[Eph. 4:7-13] The First Epistle to Timothy (c. 90-140) describes Jesus as taken up in glory.[Tim. 3:16] The traditional ending of Mark[16:19] includes a summary of Luke's resurrection material and describes Jesus as being taken up into heaven and sitting at God's right hand. The imagery of Jesus' Ascension is related to the broader theme of his exaltation and heavenly welcome, derived from the Hebrew Bible. The image of Jesus rising bodily into the heavens reflects the ancient view that heaven was above the earth. Belief in the Ascension of Jesus is found in the Nicene Creed, and is affirmed by Christian liturgy and, in the West, by the Apostles' Creed. The Ascension implies Jesus' humanity being taken into heaven. Ascension Day, celebrated 40 days after Easter, is one of chief feasts of the Christian year. The feast dates back at least to the later 300s, as is widely attested. The canonical account of Jesus ascending bodily into the clouds contrasts with the gnostic tradition, by which Jesus was said to transcend the physical realm and return to his home in the spirit world. It also contrasts with the beliefs of Docetism, in which matter is intrinsically evil and Jesus was said to have been pure spirit.

Corpus Christi (Latin for Body of Christ) is a Western Catholic feast. It is also celebrated in some Anglican and Lutheran churches. It honors the Eucharist, which believers consider to be the actual body and blood of Christ, and as such it does not commemorate a particular event in Jesus' life. It is held on the Thursday after Trinity Sunday or, in some places, on the following Sunday. Its celebration on a Thursday is meant to associate it with Jesus' institution of the Eucharist during the Last Supper, commemorated on Maundy Thursday, and this is the first free Thursday after Paschaltide. In the Ordinary Form of the Catholic Church, the feast is officially known as the Solemnity of the Most Holy Body and Blood of Christ. In many English-speaking countries, Corpus Christi is transferred to the Sunday after Trinity Sunday by both Catholics and Anglicans. At the end of the Mass, it is customary to have a Procession of the Blessed Sacrament (often outdoors), followed by Benediction of the Blessed Sacrament.

According to the belief of Christians of the Catholic Church, the Eastern Orthodox, and Oriental Orthodox churches and by some Anglicans, the Assumption of Mary was the bodily taking up of the Virgin Mary into Heaven at the end of her life. The Catholic Church teaches as dogma that Mary, "having completed the course of her earthly life, was assumed body and soul into heavenly glory." This doctrine was dogmatically and infallibly defined by Pope Pius XII on November 1, 1950, in his Apostolic Constitution Munificentissimus Deus. This belief is known as the Dormition by the Orthodox. In the churches which observe it, the Assumption is a major festival, commonly celebrated on August 15. In many countries it is a Catholic Holy Day of Obligation. In his August 15, 2004, homily given at Lourdes, Pope John Paul II quoted John 14:3 as one of the scriptural bases for understanding the dogma of the Assumption of Mary. In this verse, Jesus tells his disciples at the Last Supper, "If I go and prepare a place for you, I will come again, and will receive you to myself; that where I am, you may be there also." According to Catholic theology, Mary is the pledge of the fulfillment of Christ's promise.

All Saints' Day (in the Catholic Church officially the Solemnity of All Saints and also called All Hallows or Hallowmas), often shortened to All Saints, is a solemnity celebrated on 1 November in Western Christianity, and on the first Sunday after Pentecost in Eastern Christianity, in honour of all the saints, known and unknown. In terms of Western Christian theology, the day commemorates all those who have attained the beatific vision in Heaven. In the Roman Catholic Church, the next day, All Souls' Day, specifically commemorates the departed faithful who have not yet been purified and reached heaven. It is a national holiday in many historically Catholic countries.

All Saints' Day (in the Catholic Church officially the Solemnity of All Saints and also called All Hallows or Hallowmas), often shortened to All Saints, is a solemnity celebrated on 1 November in Western Christianity, and on the first Sunday after Pentecost in Eastern Christianity, in honour of all the saints, known and unknown. In terms of Western Christian theology, the day commemorates all those who have attained the beatific vision in Heaven. In the Roman Catholic Church, the next day, All Souls' Day, specifically commemorates the departed faithful who have not yet been purified and reached heaven. It is a national holiday in many historically Catholic countries.

Christmas Eve is the day before Christmas Day, a widely celebrated holiday commemorating the birth of Jesus of Nazareth. It is a culturally significant celebration for most of the Western world and is widely observed as a full or partial holiday in anticipation of Christmas. In Western culture, Christmas Eve is celebrated on December 24. However, the Coptic, Serbian, Russian, Macedonian, and Georgian Orthodox Churches, as well as the Greek Orthodox Church of Jerusalem, use the Julian calendar, which is currently thirteen days behind the Gregorian calendar, so Christmas Eve for the adherents of those Churches coincides with January 6 of the following year in the Gregorian calendar.

Christmas or Christmas Day is an annual Christian holiday commemorating the birth of Jesus Christ. It is celebrated on December 25, but this date is not known to be Jesus' actual birthday, and may have initially been chosen to correspond with either the day exactly nine months after some early Christians believed Jesus had been conceived, a historical Roman festival, or the date of the northern hemisphere's winter solstice. Christmas is central to the Christmas and holiday season, and in Christianity marks the beginning of the larger season of Christmastide, which lasts twelve days

Boxing Day is a bank and public holiday commonly occurring on the 26th of December. It is observed in the United Kingdom, Australia, Canada, Ghana, Switzerland, Germany, Greenland, Netherlands, New Zealand, Hong Kong, Nigeria,Kenya, Guyana, Trinidad & Tobago, Jamaica and countries in the Commonwealth of Nations with a mainly Christian population. In South Africa this public holiday is now known as the Day of Goodwill. Though it is not an official holiday in the United States, the term "Boxing Day" is used by some Americans, particularly those that live near the Canada – United States border. In Canada, Boxing Day is listed in the Canada Labour Code as a holiday. It is not an official holiday in Quebec or British Columbia. The traditional recorded celebration of Boxing Day has long included giving money and other gifts to those who were needy and in service positions. The European tradition has been dated to the Middle Ages, but the exact origin is unknown and there are some claims that it goes back to the late Roman/early Christian era; metal boxes were placed outside churches used to collect special offerings tied to the Feast of Saint Stephen. In the United Kingdom it certainly became a custom of the nineteenth century Victorians for tradesmen to collect their "Christmas boxes" or gifts in return for good and reliable service throughout the year on the day after Christmas. However, the exact etymology of the term "Boxing" is unclear, with several competing theories, none of which is definitively true. Another possibility is that the name derives from an old English tradition: in exchange for ensuring that wealthy landowners' Christmases ran smoothly, their servants were allowed to take the 26th off to visit their families. The employers gave each servant a box containing gifts and bonuses (and sometimes leftover food). In addition, around the 1800s, churches opened their alms boxes (boxes where people place monetary donations) and distributed the contents to the poor.