Seventh-day Adventists, Seventh Day Baptists and several other Christian groups continue to follow the biblical injunction to "remember the Sabbath day by keeping it holy" (Exodus 20:8). They "keep" Saturday as their Sabbath because the fourth commandment says, "The seventh day is a Sabbath to the Lord your God" (Exodus 20:10).
On the other hand, while there is no biblical justification for making the first day of the week, Sunday, the day of rest and worship, most Christians do worship on that day. Why did people start this practice? And when did they make the transition from Saturday to Sunday?
There are no extrabiblical historical references to the observance of Sunday prior to A.D. 100. However, there is significant evidence for Sunday observance soon after the turn of the first century. This does not mean that the change was abrupt. Observance of the seventh day (which I'll call Sabbath in this article) continued alongside the observance of Sunday for several centuries. The adoption of Sunday was a gradual process. Three factors prompted the change from Sabbath to Sunday: anti-Judaism, sun worship and the influence of the church in Rome.
In Roman times, a religion had to have official recognition in order to exist. People who believed and practiced an unauthorised religion were persecuted. In its early years, the Christian church escaped this religious persecution by operating under the umbrella of Judaism, which Rome recognised. However, Jewish revolts against Rome brought a drastic change. Following the second rebellion in A.D. 135, the Emperor Hadrian made Jerusalem a Roman colony from which Jews, including Jewish Christians, were excluded. Hadrian outlawed the practice of Judaism in general and of Sabbath keeping in particular throughout the empire.
At this time, the Christian church began to produce a lot of anti-Jewish literature. Christians developed a theology of separation from and contempt toward the Jews, castigating Jewish customs such as circumcision and Sabbath keeping. The earliest known record of this Christian separation from Judaism is found in an ancient document called the "Epistle to the Magnesians," written by Ignatius, bishop of Antioch sometime in the late first century AD. He said, "If we are still practicing Judaism, we admit that we have not received God's favour."
The Epistle of Barnabas, probably written in Alexandria between A.D. 130-138, speaks of the observance of "the eighth day"-at that time a common designation for the first day of the week. The author described the Jews as wretched people whom God abandoned because they killed His prophets and crucified Christ. Opposition to Judaism was his major argument for observing the "eighth day."
Justin Martyr, another influential Christian who opposed the Sabbath, lived in Rome around the middle of the second century A.D. His opposition was motivated, at least in part, by a bitter hatred he held toward the Jews, who, he said, treated Christians even more unjustly than did the Gentile nations. Justin endorsed the observance of the first day of the week.
The social, political and religious conditions mentioned above explain why Christians began to turn from the day of worship that they shared with the Jews. They do not explain, however, why Christians began to observe Sunday rather than another day, such as Friday, the day of Christ's crucifixion. The influence of sun worship with its "sun day" provides the most plausible explanation.
The cult of Sol Invictus, the "Invincible Sun," became dominant in Rome and in other parts of the empire during the early part of the second century A.D. And evidence abounds that Roman sun cults influenced Christian thought and liturgy. On the one hand, the church fathers frequently rebuked Christians for venerating the sun. On the other hand, in early Christian art and literature, the sun is often used as a symbol to represent Christ. Instead of facing Jerusalem, as the synagogues did, early Christian churches were oriented to the east. And Christians chose "the birthday of the Invincible Sun" as their day to celebrate Christ's birth (Christmas).
A second-century change in the Roman calendar may also have influenced the switch. The Roman Empire adopted the seven-day week in the first century A.D. At that time the days of the week were named after the planets, the first day of the week being designated Saturn's day (Saturday), and the second day the day of the sun. Under the influence of sun worship, however, a change occurred in the second century: The sun's day was advanced to the first and most important day of the week. This advancement of the day of the sun presumably influenced Roman Christians with a pagan background to adopt the sun's day for their worship also. Doing so would have emphasised to pagan Romans the Christian acceptance of Roman practices and their rejection of Jewish customs.
Whatever their motivation, the leaders of the early church used the motifs of light and of the sun to justify their observance of Sunday. Jerome, for instance, explained that "if it is called the day of the sun by the pagans, we most willingly acknowledge it as such, since it is on this day that the light of the world appeared and on this day the Sun of Justice [Jesus Christ] has risen." The day of the sun, then, may well have been viewed by Christians familiar with its veneration as a providential and valid substitution for the Sabbath, since the substitution allowed them to explain biblical mysteries by means of symbols familiar to the pagan mind.
the church at Rome
The church at Rome, the most powerful church in the Roman Empire, played a major role in this matter. We find in it the social, religious and political conditions that permitted and encouraged the abandonment of Sabbath keeping and the adoption instead of Sunday worship.
Unlike most Eastern churches, the church at Rome consisted primarily of Gentile converts. This factor apparently contributed to this church's early differentiation from the Jews. We note as evidence, for instance, that in A.D. 64 Nero placed the charge of arson exclusively on Christians, thus recognising at that early date their distinction from the Jews.
The church at Rome adopted concrete measures to wean Christians away from Sabbath keeping and to encourage Sunday worship in its place. Justin Martyr said the observance of the Sabbath was a temporary Mosaic ordinance that God imposed exclusively on the Jews as "a mark to single them out for punishment they so well deserve for their infidelities."
This kind of negative reinterpretation of the Sabbath led Christians to transform their Sabbath observance. They turned the day that earlier believers had observed with feasting, joy and religious celebration into a day of fasting in which no eucharistic celebration or religious assemblies were permitted. This Saturday fast served not only to express sorrow for Christ's death, but also, as Pope Sylvester (pope from A.D. 314-335) emphatically stated, to show contempt for the Jews and their Sabbath feasting. The sadness and hunger resulting from the fast would enable Christians to avoid "appearing to observe the Sabbath with the Jews" and would encourage them to enter more eagerly and joyfully into the observance of Sunday.
Because the basic function of the Saturday fast was to discourage Sabbath keeping and to enhance Sunday worship, it seems likely that the Saturday fast and Sunday worship both originated contemporaneously and at the same place. There is no question that the church at Rome introduced the Saturday fast.
Moreover, since the church fathers frequently presented the weekly and the annual Saturday fasts and the weekly Sunday and Easter Sunday observances as interrelated in their meaning and function, presumably all these practices originated at the same time.
Late in the second century A.D., a dispute arose in the Christian church as to whether to celebrate Jesus' death and resurrection on the Jewish Passover (the 14th day of the Jewish month of Nisan, which rotates through the days of the week) or on Sunday. Irenaeus, bishop of Lyon, who intervened as peacemaker in the controversy, mentions Bishop Sixtus, bishop of the church at Rome (about A.D. 116- 126), as the first bishop who did not follow the Passover date. That suggests the possibility that the feast began to be celebrated on Sunday in Rome at about that time.
While the exact date of the origin of Easter Sunday may be a subject of dispute, most scholars agree that the new custom was introduced in Rome to avoid "even the semblance of Judaism." Constantine, in his letter to the Christian bishops at the Council of Nicaea (A.D. 325) exemplifies the marked anti-Judaic motivation for the repudiation of the connection between Passover and Easter. He wrote, "We ought not therefore to have anything in common with the Jews, for the Saviour has shown us another way. . . . In unanimously adopting this mode [i.e., Easter Sunday], we desire, dearest brethren, to separate ourselves from the detestable company of the Jews."
The same anti-Judaic motivations that caused the replacement of the Jewish Passover with Easter Sunday also accounts for the contemporaneous substitution of Sabbath keeping with Sunday worship. This argument is supported not only by the fact that the Jewish Sabbath shared the same anti-Judaic condemnation as the Jewish Passover, but also by the close connection between the observance of the annual Easter Saturday-Sunday (a fast followed by a day of joy) and that of its weekly counterpart (the Saturday fast followed by Sunday worship). The church fathers explicitly affirmed the basic unity between these annual and weekly observances, further suggesting a common origin in the church at Rome.
Another important consideration is that the bishop of Rome exercised "preeminent authority" among the Christian churches. He was the only one capable at that time of influencing the majority of Christians to adopt new religious observances.
So, it seems clear that Sunday observance in Christianity originated in Rome in the early part of the second century (about A.D. 135).
Scholars believe that the Epistle of Barnabas was written by someone other than Paul's associate.