The Lord's Day in Christianity is generally Sunday, the principal day of communal worship. It is observed by most Christians as the weekly memorial of the resurrection of Jesus Christ, who is said in the canonical Gospels to have been witnessed alive from the dead early on the first day of the week. The phrase appears in Rev. 1:10.
According to some sources, Christians held corporate worship on Sunday in the 1st century. The earliest Biblical example of Christians meeting together on a Sunday for the purpose of "breaking bread" and preaching is cited in the New Testament book The Acts of the Apostles chapter 20 and verse 7 (Acts 20:7). 2nd-century writers such as Justin Martyr attest to the widespread practice of Sunday worship (First Apology, chapter 67), and by 361 AD it had become a mandated weekly occurrence. During the Middle Ages, Sunday worship became associated with Sabbatarian (rest) practices. Some Protestants today (particularly those theologically descended from the Puritans) regard Sunday as Christian Sabbath, a practice known as first-day Sabbatarianism. (Some Christian groups hold that the term "Lord's Day" can only properly refer to seventh-day Sabbath or Saturday.)
Sunday was also known in patristic writings as the eighth day.
The phrase the "Lord's Day" appears only once in the Bible in Revelation 1:10 which was written near the end of the first century. It is the English translation of the koine Greek kyriake hemera. The adjective kyriake ("Lord's") often elided its noun, as in the neuter kyriakon for "Lord's [assembly]", the predecessor of the word "church"; the noun was to be supplied by context.
In Rev. 1:10, the apostle John, used kyriake hemera ("I was in the Spirit on the Lord's Day") in a way apparently familiar to his readers. Observers of first-day worship hold that this means he was worshiping on Sunday, resurrection day. Seventh-day Sabbatarians hold that since Jesus said he was "Lord of the Sabbath" and that Isaiah called the Sabbath the "Lord's Holy Day" then the Lord's Day is the Seventh-day Sabbath (i.e. Saturday). Both parties accordingly use this verse to lay claim to the name "Lord's Day" for their day of worship.
The term "Lord's" appears in The Teaching of the Twelve Apostles or Didache, a document dated between 70 and 120. Didache 14:1a is translated by Roberts as, "But every Lord's day gather yourselves together, and break bread, and give thanksgiving"; another translation begins, "On the Lord's own day". The first clause in Greek, "κατά κυριακήν δέ κυρίου", literally means "On the Lord's of the Lord", a unique and unexplained double possessive, and translators supply the elided noun, e.g., "day" (ἡμέρα hemera), "commandment" (from the immediately prior verse 13:7), or "doctrine". This is one of two early extrabiblical Christian uses of "κυριακήν" where it does not clearly refer to Sunday because textual readings have given rise to questions of proper translation. Breaking bread (daily or weekly) may refer to Christian fellowship, agape feasts, or Eucharist (cf. Acts 2:42, 20:7). Didache 14 was apparently understood by the writers of the Didascalia and Apostolic Constitutions as a reference to Sunday worship.
Around 110 AD, St. Ignatius of Antioch used "Lord's" in a passage of his letter to the Magnesians. Ambiguity arises due to textual variants. The only extant Greek manuscript of the letter, the Codex Mediceo-Laurentianus, reads, "If, then, those who had walked in ancient practices attained unto newness of hope, no longer observing Sabbath, but living according to the Lord's life ..." (kata kyriaken zoen zontes). A medieval Latin translation indicates an alternate textual reading of kata kyriaken zontes, informing Roberts's translation, "no longer observing the Sabbath, but living in the observance of the Lord's [Day]".
The expanded Pseudo-Ignatian version of Magnesians, from the middle of the third century, rewrites this passage to make "Lord's Day" a clear reference to Sunday, as Resurrection Day. Pseudo-Ignatius adds a repudiation of legalistic Sabbath as a Judaizing error: "Let us therefore no longer keep the Sabbath after the Jewish manner, and rejoice in days of idleness .... But let every one of you keep the Sabbath after a spiritual manner, rejoicing in meditation on the law, not in relaxation of the body, admiring the workmanship of God, and not eating things prepared the day before, nor using lukewarm drinks, and walking within a prescribed space, nor finding delight in dancing and plaudits which have no sense in them. And after the observance of the Sabbath, let every friend of Christ keep the Lord’s Day as a festival, the resurrection-day, the queen and chief of all the days." Other early church fathers similarly saw weekly observance of seventh-day Sabbath sometimes followed the next day by Lord's Day assembly.
The first undisputed reference to Lord's Day is in the apocryphal Gospel of Peter (verse 34,35 and 50), probably written about the middle of the 2nd century or perhaps the first half of that century. The Gospel of Peter 35 and 50 use kyriake as the name for the first day of the week, the day of Jesus' resurrection. That the author referred to Lord's Day in an apocryphal gospel purportedly written by St. Peter indicates that the term kyriake was very widespread and had been in use for some time.
Around 170 AD, Dionysius, Bishop of Corinth, wrote to the Roman Church, "Today we have kept the Lord's holy day (kyriake hagia hemera), on which we have read your letter." In the latter half of the 2nd century, the apocryphal Acts of Peter identify Dies Domini (Latin for "Lord's Day") as "the next day after the Sabbath," i.e., Sunday. From the same period of time, the Acts of Paul present St. Paul praying "on the Sabbath as the Lord's Day (kyriake) drew near." However, the Lord's day is identified with the Sabbath in the Acts of John as "on the seventh day, it being the Lord's day, he said to them: now it is time for me also to partake of food."
In the first centuries, Sunday, being made a festival in honor of Christ's resurrection, received attention as a day of religious services and recreation, but seventh-day Sabbath rest (based on the Jewish Shabbat, because the earliest Christians were all Jews) was still observed by "almost all churches". Often first-day worship (Sunday morning or Saturday night) was practiced alongside observance of seventh-day Sabbath rest and was a widespread Christian tradition by the 2nd century, attested in patristic writings of the 2nd century; over time, Sunday thus came to be known as Lord's Day. These early Christians believed that the resurrection and ascension of Christ signals the renewal of creation, making the day on which God accomplished it a day analogous to the first day of creation when God made the light. Some of these writers referred to Sunday as the "eighth day".
The 1st-century or 2nd-century Epistle of Barnabas or Pseudo-Barnabas on Is. 1:13 stated "Sabbaths of the present age" were abolished in favor of one millennial seventh-day Sabbath that ushers in the "eighth day" and commencement of a new world. Accordingly, the eighth-day assembly (Saturday night or Sunday morning) marks both the resurrection and the new creation. Thus first-day observance was a common regional practice at that time.
By the mid-2nd century, Justin Martyr wrote in his apologies about the cessation of Sabbath observance and the celebration of the first (or eighth) day of the week (not as a day of rest, but as a day for gathering to worship): "We all gather on the day of the sun" (τῇ τοῦ ῾Ηλίου λεγομένη ἡμέρᾳ, recalling both the creation of light and the resurrection). He argued that Sabbath was not kept before Moses, and was only instituted as a sign to Israel and a temporary measure because of Israel's sinfulness, no longer needed after Christ came without sin. Curiously he also draws a parallel between the Israelite practice of circumcision on the eighth day, and the resurrection of Jesus on the "eighth day".
But the Gentiles, who have believed on Him, and have repented of the sins which they have committed, they shall receive the inheritance along with the patriarchs and the prophets, and the just men who are descended from Jacob, even although they neither keep the Sabbath, nor are circumcised, nor observe the feasts.
And on the day called Sunday, all who live in cities or in the country gather together to one place, and the memoirs of the apostles or the writings of the prophets are read, as long as time permits; then, when the reader has ceased, the president verbally instructs, and exhorts to the imitation of these good things. Then we all rise together and pray, and, as we before said, when our prayer is ended, bread and wine and water are brought, and the president in like manner offers prayers and thanksgivings, according to his ability, and the people assent, saying Amen; and there is a distribution to each, and a participation of that over which thanks have been given, and to those who are absent a portion is sent by the deacons. And they who are well to do, and willing, give what each thinks fit; and what is collected is deposited with the president, who succours the orphans and widows and those who, through sickness or any other cause, are in want, and those who are in bonds and the strangers sojourning among us, and in a word takes care of all who are in need. But Sunday is the day on which we all hold our common assembly, because it is the first day on which God, having wrought a change in the darkness and matter, made the world; and Jesus Christ our Saviour on the same day rose from the dead.
Tertullian (early 3rd century), writing against Christians who participated in pagan festivals (Saturnalia and New-year), defended the Christian festivity of Lord's Day amidst the accusation of sun-worship, acknowledging that "to [us] Sabbaths are strange" and unobserved.
Cyprian, a 3rd-century church father, linked the "eighth day" with the term "Lord's Day" in a letter concerning baptism.
'For in respect of the observance of the eighth day of the Jewish circumcision of the flesh, a sacrament was given beforehand in shadow and in usage; but when Christ came, it was fulfilled in truth. For because the eighth day, that is, the first day after the Sabbath, was to be that on which the Lord should rise again, and should quicken us, and give us circumcision of the spirit, the eighth day, that is the first day after the Sabbath, and the Lord's Day, went before in the figure; which figure ceased when by and by the truth came and spiritual circumcision was given to us— Cyprian, Letter LVIII
Though Sunday was widely observed as a day of Christian worship by the 2nd century, the origin of Sunday worship remains a debated point, with at least three scholarly positions being taken.
On 3 March 321, Constantine I decreed that Sunday (dies Solis) will be observed as the Roman day of rest [CJ3.12.2]:
On the venerable day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed. In the country however persons engaged in agriculture may freely and lawfully continue their pursuits because it often happens that another day is not suitable for grain-sowing or vine planting; lest by neglecting the proper moment for such operations the bounty of heaven should be lost.
In the 4th century, Socrates Scholasticus stated that the Christians of Alexandria and Rome partook of the "mysteries" (the love feast or Eucharist) on the first day of the week (Saturday evening), though they also held worship meetings on Sabbath like almost all other churches. By the 5th century, Sozomen stated that most churches, such as at Constantinople, met both on Sabbath and first day (Saturday evening), but that Rome and Alexandria met only on the first day (Saturday evening) and no longer on Sabbath.
Augustine of Hippo followed the early patristic writers in spiritualizing the meaning of the Sabbath commandment, referring it to eschatological rest rather than observance of a literal day. However, the practice of Sunday rest increased in prominence throughout the early Middle Ages. Thomas Aquinas taught that the decalogue is an expression of natural law which binds all men, and therefore the Sabbath commandment is a moral requirement along with the other nine. Thus Sunday rest and Sabbath became increasingly associated.
Following Aquinas' decree, Christian Europeans could now spend less time denouncing the Judaistic method of observing the Sabbath, instead establishing rules for what one "should" and "should not" do on the Sabbath. For example, while the Medieval Church forbade most forms of work on the Sabbath, it allowed "necessary works", and priests would allow their peasants to perform the needed agricultural work in the field.
The reformers Martin Luther and John Calvin repudiated the idea that Christians are bound to obey the Mosaic law, including the fourth commandment of the decalogue concerning Sabbath, although they followed Aquinas' concept of natural law. They viewed Sunday rest as a civic institution established by human authority, which provided an occasion for bodily rest and public worship.
Nevertheless, Sunday Sabbatarianism became prevalent amongst both the continental and English Protestants over the following century. A new rigorism was brought into the observance of Lord's Day among the 17th-century Puritans of England and Scotland, in reaction to the laxity with which Sunday observance was customarily kept. Sabbath ordinances were appealed to, with the idea that only the word of God can bind men's consciences in whether or how they will take a break from work, or to impose an obligation to meet at a particular time. Their influential reasoning spread to other denominations also, and it is primarily through their influence that "Sabbath" has become the colloquial equivalent of "Lord's Day" or "Sunday". The most mature expression of this influence survives in the Westminster Confession of Faith (1646), Chapter 21, "Of Religious Worship, and the Sabbath Day". Section 7-8 reads:
7. As it is the law of nature, that, in general, a due proportion of time be set apart for the worship of God; so, in his Word, by a positive, moral, and perpetual commandment binding all men in all ages, he hath particularly appointed one day in seven, for a Sabbath, to be kept holy unto him: which, from the beginning of the world to the resurrection of Christ, was the last day of the week; and, from the resurrection of Christ, was changed into the first day of the week, which, in Scripture, is called the Lord’s day, and is to be continued to the end of the world, as the Christian Sabbath.
8. This Sabbath is then kept holy unto the Lord, when men, after a due preparing of their hearts, and ordering of their common affairs beforehand, do not only observe a holy rest, all the day, from their own works, words, and thoughts about their worldly employments and recreations, but also are taken up, the whole time, in the public and private exercises of his worship, and in the duties of necessity and mercy.
Though Sabbatarian practice declined in the 18th century, the evangelical awakening in the 19th century led to a greater concern for strict Sunday observance. The founding of the Lord's Day Observance Society in 1831 was influenced by the teaching of Daniel Wilson.
Jehovah's Witnesses believe that Lord's day begun in 1914, that was the year marked by 1st world war and has direct connection with the prophecy in Revelation (Rev 12:7). The prophecy is about the war in heaven and the ouster of Devil from heaven. Lord's day is not a single day consisting of 24 hours, but a period of time that started in 1914 which will last for sometime that includes Christ's Thousand year reign.
The Second Vatican Council, in the Apostolic Constitution Sacrosanctum Concilium, asserted that "the Lord's day is the original feast day" and the "foundation and kernel of the whole liturgical year." The apostolic letter of Pope John Paul II entitled Dies Domini charged Catholics to remember the importance of keeping Sunday holy and not to confuse the holiness of the Lord's Day celebration with the common notion of the weekend as a time of simple rest and relaxation.
The Eastern Orthodox Church distinguishes between "Sabbath" (Saturday) and "Lord's Day" (Sunday), and both continue to play a special role for the faithful. Many parishes and monasteries will serve the Divine Liturgy on both Saturday morning and Sunday morning. The church never allows strict fasting on any Saturday (except Holy Saturday) or Sunday, and the fasting rules on those Saturdays and Sundays which fall during one of the fasting seasons (such as Great Lent, Apostles' Fast, etc.) are always relaxed to some degree. During Great Lent, when the celebration of the Liturgy is forbidden on weekdays, there is always Liturgy on Saturday as well as Sunday. The church also has a special cycle of Bible readings (Epistle and Gospel) for Saturdays and Sundays which is different from the cycle of readings allotted to weekdays. However, Lord's Day, being a celebration of the Resurrection, is clearly given more emphasis. For instance, in the Russian Orthodox Church Sunday is always observed with an All-Night Vigil on Saturday night, and in all of the Orthodox Churches it is amplified with special hymns which are chanted only on Sunday. If a feast day falls on a Sunday it is always combined with the hymns for Sunday (unless it is a Great Feast of the Lord). Saturday is celebrated as a sort of leave-taking for the previous Sunday, on which several of the hymns from the previous Sunday are repeated.
In part, the reason Orthodox Christians continue to celebrate Saturday as Sabbath is because of its role in the history of salvation: it was on a Saturday that Jesus "rested" in the tomb after his work on the cross. For this reason also, Saturday is a day for general commemoration of the departed, and special requiem hymns are often chanted on this day.
For although almost all churches throughout the world celebrate the sacred mysteries on the sabbath of every week, yet the Christians of Alexandria and at Rome, on account of some ancient tradition, have ceased to do this. The Egyptians in the neighborhood of Alexandria, and the inhabitants of Thebaïs, hold their religious assemblies on the sabbath, but do not participate of the mysteries in the manner usual among Christians in general: for after having eaten and satisfied themselves with food of all kinds, in the evening making their offerings they partake of the mysteries.
Assemblies are not held in all churches on the same time or manner. The people of Constantinople, and almost everywhere, assemble together on the Sabbath, as well as on the first day of the week, which custom is never observed at Rome or at Alexandria. There are several cities and villages in Egypt where, contrary to the usage established elsewhere, the people meet together on Sabbath evenings, and, although they have dined previously, partake of the mysteries.
'And your new moons and sabbaths I cannot endure.' He has therefore abolished these things .... Ye perceive how He speaks: Your present Sabbaths are not acceptable to Me, but that is which I have made, [namely this,] when, giving rest to all things, I shall make a beginning of the eighth day, that is, a beginning of another world. Wherefore, also, we keep the eighth day with joyfulness, the day also on which Jesus rose again from the dead. And when He had manifested Himself, He ascended into the heavens.
By us, to whom Sabbaths are strange, and the new moons and festivals formerly beloved by God, the Saturnalia and New-year's and Midwinter's festivals and Matronalia are frequented--presents come and go--New-year's gifts--games join their noise--banquets join their din! Oh better fidelity of the nations to their own sect, which claims no solemnity of the Christians for itself! Not the Lord's day, not Pentecost, even it they had known them, would they have shared with us; for they would fear lest they should seem to be Christians. We are not apprehensive lest we seem to be heathens! If any indulgence is to be granted to the flesh, you have it. I will not say your own days, but more too; for to the heathens each festive day occurs but once annually: you have a festive day every eighth day.
Others, with greater regard to good manners, it must be confessed, suppose that the sun is the god of the Christians, because it is a well-known fact that we pray towards the east, or because we make Sunday a day of festivity.