Ignoring St. Ignatius and the Bible I give you is just unbecoming. For one who discards the Resurrection's sovereignty in Sunday observance but then presents himself as honest you are ironically a lot like the Sadduccees.
Here is a little background, as the change came from Rome and of pagan and Hellenistic ideas but the other centers of Alexandria and Antioch were even then Christians there including Ignatius was influenced by it and started to observe Sunday too. But Rome was were it was changed and later became codified by the influence of its bishop...
...Sunday is not a strict replacement for the Sabbath, but a day the Catholic Church instituted to fulfill a parallel function. Thus Ignatius of Antioch, the earliest Church Father to address this question, states that Christian converts "have given up keeping the Sabbath and now order their lives by the Lord's Day instead, the day when life first dawned for us, thanks to him [Christ] and his death." (Letter to the Magnesians 9 [A.D. 107]).
The fourth century saw the introduction of Sunday laws. First Sunday laws of a civil nature were issued, then came Sunday laws of a religious character. The emperor Constantine decreed the first civil Sunday law on March 7, A.D. 321. In view of Sunday's popularity among the pagan sun worshipers and the esteem with which many Christians regarded it, Constantine hoped that, by making Sunday a holiday, he could ensure the support of these two constituencies for his government.Constantine's Sunday law reflected his background as sun worshiper. It read: "On the venerable Day of the Sun [venerabili die Solis] 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
Yes it was the Bishop of Rome who 'officially' changed the Sabbath from Saturday to Sunday in Christendom after Constantine the Great's 321 A.D. edict. Sylvester I (314-335 A.D.) was the Bishop of Rome during the reign of Constantine who gave his "stamp of approval" to the 321 Edict. Sylvester I did this because being in the office of the Bishop of Rome, with its positional authority as it had been the center of the Roman world. Thus, nodding his approval. This change from Saturday to Sunday was then codified in the Council of Laodicea (c. A.D. 364), which was not a universal council but a Roman Catholic one, which issued the first ecclesiastical Sunday law. In canon 29 the church stipulated that Christians should honor Sunday and "if possible, do no work on that day,' while it denounced the practice of resting on the Sabbath, instructing that Christians should not "be idle on Saturday [Greek sabbaton, "the Sabbath"], but shall work on that day saying "Christians must not Judaize by resting on the Sabbath"...meaning Saturday.
Sylvester I (314-337 A.D.) was the pope during the reign of Constantine. Here is what he thought of the Bible Sabbath: "If every Sunday is to be observed joyfully by the Christians on account of the resurrection, then every Sabbath on account of the burial is to be execration [loathing or cursing] of the Jews."--quoted by S. R. E. Humbert, Adversus Graecorum calumnias 6, in Patrologie Cursus Completus, Series Latina, ed. J.P. Migne, 1844, p. 143.
From the second to the fifth centuries, while Sunday was rising in influence, Christians continued to observe the seventh-day Sabbath nearly everywhere throughout the Roman Empire. But by the fourth and fifth centuries many Christians worshiped on both Sabbath and Sunday. However, Sozomen, another historian of that period, wrote, "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." These references demonstrate Rome's leading role even then in disregarding Sabbath observance and going to Sunday. Note that not one writer of the second and third centuries ever cited a single Bible verse as authority for the observance of Sunday in the place of the Sabbath. Neither Barnabas, nor Ignatius, nor Justin, nor Irenaeus, nor Tertullian, nor Clement of Rome, nor Clement of Alexandria, nor Origen, nor Cyprian, nor Victorinus, nor any other author who lived near to the time when Jesus lived knew of any such instruction from Jesus or from any part of the Bible, it came from paganism not scripture.
Now on the impression that John was referring to Sunday when he stated he was "in the Spirit on the Lord's day" (Rev. 1:10). In the Bible, however, the only day referred to as the Lord's special possession is the Sabbath. Christ stated, "The seventh day is the Sabbath of the Lord your God" (Ex. 20:10); later calling it "My holy day" (Isa. 58:13). And Christ called Himself "Lord of the Sabbath" (Mark 2:28). Since, in the Scripture, the only day the Lord calls His own is the seventh-day Sabbath, it seems logical to conclude that it was the Sabbath to which John was referring. There is no Biblical precedent to indicate he would apply that term to the first day of the week, or Sunday.Nowhere does the Bible command us to observe any weekly day other than the Sabbath. It declares no other weekly day blessed or holy. Nor does the New Testament indicate that God has changed the Sabbath to any other day of the week.
On the contrary, Scripture reveals that God intended that His people should observe the Sabbath throughout eternity: "'As the new heavens and the new earth which I will make will remain before me,' says the Lord, 'so shall your descendants and your name remain. . . . From one New Moon to another, and from one Sabbath to another, all flesh shall come to worship before Me,' says the Lord" (Isa. 66:22, 23).
Scripture reveals that the observance of Sunday as a Christian institution was fortold and had its origin in "the mystery of lawlessness" (2 Thess. 2:7), which was already at work in Paul's day. Also through the prophecy of Daniel 7 God revealed His foreknowledge of the change of the day of worship. Daniel's vision depicts an attack on God's people and on Gods Law including the Sabbath. The power brought to bear which would do the change was represented by a little horn which would bring about the great apostasy within the Christian church. Arising from the fourth beast or Roman Empire and becoming a major persecuting power after
the fall of Rome, this power or the little horn attempts to "change the times and law" (Dan. 7:25). This apostate power is very successful at deceiving most of the world, but at the end the judgment will decide against it (Dan. 7:11, 22, 26).
Scripture shows that the change to Gods Law would be done, but it was not because God changed it or from the resurection of Christ, but from apostasy brought on by by a power of "the mystery of lawlessness", and history confirms it step by step, almost to a tee...