How Sunday Became a day of Worship for Christian
Certainly, many religious organization has given various explanation on how and why Sunday was chosen as a day of worship instead of saturday.
Some Churches has said that the Romans where responsible for the change, others doubt that if they are, then the Orthodox Churches may not have joins the Roman Catholic even if the Protestants decide to join the Roman Catholic in worshiping that day. Still others argued that a particular Roman emperor, Constantine made it that way. Let's analysis their argument and draw conclusion.
According to the Church of God International Tyler, they said and I quote ''The Christians during the apostolic era, from about 35 to 100 A.D., kept Sabbath on the designated seventh day of the week. For the first 300 years of Christian history, when the Roman emperors regarded themselves as gods, Christianity became an “illegal religion,” and God’s people were scattered abroad . Judaism, however, was regarded at that time as “legal,” as long as they obeyed Roman laws. Thus, during the apostolic era, Christians found it convenient to let the Roman authorities think of them as Jews, which gained them legitimacy with the Roman government. However, when the Jews rebelled against Rome, the Romans put down their rebellion by destroying Jerusalem in A.D. 70 and again in A.D. 135. Obviously, the Roman government’s suppression of the Jews made it increasingly uncomfortable for Christians to be thought of as Jewish. At that time, Sunday was the rest day of the Roman Empire, whose religion was Mithraism, a form of sun worship. Since Sabbath observance is visible to others, some Christians in the early second century sought to distance themselves from Judaism by observing a different day, thus “blending in” to the society around them. During the Empire-wide Christian persecutions under Nero, Maximin, Diocletian, and Galerius, Sabbath-keeping Christians were hunted down, tortured, and, for sport, often used for entertainment in the Colisseum.
When Emperor Constantine I—a pagan sun-worshipper—came to power in A.D. 313, he legalized Christianity and made the first Sunday-keeping law. His infamous Sunday enforcement law of March 7, A.D. 321, reads as follows: “On the venerable Day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed.” (Codex Justinianus 3.12.3, trans. Philip Schaff, History of the Christian Church, 5th ed. (New York, 1902), 3:380, note 1.)
The Sunday law was officially confirmed by the Roman Papacy. The Council of Laodicea in A.D. 364 decreed, “Christians shall not Judaize and be idle on Saturday but shall work on that day; but the Lord’s day they shall especially honour, and, as being Christians, shall, if possible, do no work on that day. If, however, they are found Judaizing, they shall be shut out from Christ” (Strand, op. cit., citing Charles J. Hefele, A History of the Councils of the Church, 2 [Edinburgh, 1876] 316). ''
From their argument the Romans had changed the date. But another religious organization has its own opposite view of it. The intelligent quote Say's "If Rome changed the Sabbath to Sunday, it would only explain why Protestants and Roman Catholics worship on Sunday. It would not explain why Orthodox Christians worship on Sunday, and it certainly would not explain why Syriac, the Armenian, and Coptic Christians worship on Sunday, because they had very little contact with Rome until modern times. For example, the Armenian Apostolic Church does not celebrate Christmas, which originated in Rome in the fourth century. Instead, they celebrate the nativity of Jesus Christ on Epiphany. Rome could only have changed the day of worship before the fall of the Roman Empire, because after then communications weren’t good enough. However, during that period, Rome did not have much influence in the east.
Constantine converted to Christianity after winning the battle of the Milvian Bridge. He wasn’t a very bright man and he did not have a coherent personal theology. After he became emperor, he reformed the tax system, passed laws protecting widows and orphans, donated money to churches, and sent his mother Helen to the Holy Land to preserve and restore all those sites that tourists visit even today. He passed a law that made all religions legal, and that ended the persecution of Christians. He convened and paid for the first ecumenical council in AD 325, but he was unable to understand the debates, let alone participate in them. He also changed the Roman week from ten days to seven days, so that Sunday, the Christian day of worship would always be a holiday. He did not make Christianity the state religion or do any of the other evil things often attributed to him—they were actually done by his successor, Theodosius, eighty years later. When Constantine instituted the seven-day week, he did it because Christians were already worshiping on Sunday and his purpose was to make it easier for them.
No one ever moved the Sabbath. In fact, if you look on page 283 of the Book of Common Prayer of the US Episcopal Church, you will find a service for Holy Saturday, the day before Easter Day. There is a prayer on that page that says, “O God, creator of heaven and earth: Grant that, as the crucified body of your dear Son was laid in the tomb and rested on this holy Sabbath, so we may await with him...”
From the research I've done so far I opined that the selection of Sunday as a day for worship is for philosophical and scientific reasons. Remember there were ten days in the week and Sunday begins each week. Philosophers then were highly placed. They also believed in religion. They felt it is better to worship on the first day of the week and then use the other days for work. Although philosophy had play a part in developing regions of the Roman empire. It is also important to note that the first century Christian worship almost very time. Because of the persecution they faced both from the Jews and the Romans they had to worship God when ever it is good for them. Therefore worship is done on Sundays not as a custom actually but for conviniency sake. So you can decide to worship on monday, Tuesday, or any other day in the week. When we worship during the week, we should not say it is a lesser worship than sunday. The same seriousness should be attached to it.