In The Teaching of the Twelve Apostles (one of the first books of the church in addition to the Bible, written between approximately A.D. 75 and A.D. 90, the same era as the book of Revelation), it says, “But every Lord’s day do ye gather yourselves together, and break bread, and give thanksgiving after having confessed your transgressions, that your sacrifice may be pure” (Alexander Roberts and James Donaldson, eds., The Ante-Nicene Fathers. Grand Rapids: Wm. B. Eerdmans Publishing Company, 1979. Vol. VII, p. 381). This clearly shows us that believers met together on the Lord’s Day as early as the end of the first century.
The apostle John had a disciple called Ignatius who was born in A.D. 30 and martyred in A.D. 107. In A.D. 100 he wrote an epistle to the Magnesians. In chapter nine of this epistle, he stated clearly, “If, therefore, those who were brought up in the ancient order of things [referring to those in Judaism] have come to the possession of a new hope, no longer observing the Sabbath, but living in the observance of the Lord’s Day, on which also our life has sprung up again by Him and by His death...” (ibid., Vol. I, p. 62). This clearly shows us that the early church did not keep the Sabbath but kept the Lord’s Day instead.
In about A.D. 120, Barnabas (not the Barnabas in the Bible) wrote an epistle. In chapter fifteen there was a phrase, “Wherefore, also, we keep the eighth day with joyfulness, the day also on which Jesus rose again from the dead” (ibid., Vol. I, p. 147).
Another well-known church father was Justin Martyr. He was born in A.D. 100 and was martyred in A.D. 165. In A.D. 138, he wrote a book called The First Apology. In that book he said, “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 Savior on the same day rose from the dead. For He was crucified on the day before that of Saturn (Saturday); and on the day after that of Saturn, which is the day of the Sun, having appeared to His apostles and disciples, He taught them these things, which we have submitted to you also for your consideration” (ibid., Vol. I, p. 186). In another place he wrote, “We are circumcised from deceit and iniquity through Him who rose from the dead on the first day after the Sabbath, [namely through] our Lord Jesus Christ. For the first day after the Sabbath, remaining the first of all the days, is called, however, the eighth, according to the number of all the days of the cycle, and [yet] remains the first” (ibid., Vol. I, p. 215).
In A.D. 170, there was a church father in the church in Sardis named Mileto. In his writings is this sentence, “Today we have passed the Lord’s Resurrection day. During this time, we read many epistles” (source unknown).
There was a famous church father called Clement in the city of Alexandria in A.D. 194. He said, “Today, the seventh day, has become a day of work, which is also a common working day.” Following this, he said, “We should keep the Lord’s Day” (ibid., Vol. II, p. 545).
In A.D. 200, the church father Tertullian said, “On the Lord’s Day we are especially joyful. We keep this day which is the day of our Lord’s resurrection. There is no hindrance and no worry.” At that time, some had already criticized keeping the Lord’s Day as a worshipping of the sun. So Tertullian replied saying, “We rejoice on the Lord’s Day. We do not worship the sun. We are different from those who are lazy and feasting on Saturday” (ibid., Vol. III, p. 123).
Origen was another famous person among the church fathers. He was a famous theologian in Alexandria. He said, “To keep the Lord’s Day is a mark of a complete Christian” (ibid., Vol. IV, p. 647).
Some have said that the ancient believers kept the Sabbath, and that Constantine changed it to the keeping of the first day of the week in the fourth century. This is not according to the facts. Constantine did not change this day at all. He only recognized this practice; the church had been keeping the Lord’s Day for a long time already. Before A.D. 313 the Christians were persecuted. After A.D. 313 Constantine ruled over Rome and issued an edict in Milan to stop the persecution of Christians. In A.D. 321 Constantine issued a second edict in which he wrote, “On the Lord’s Day, officers and common people, those who live in the city, should rest and all work should be stopped” (Philip Schaff and Henry Wace, eds., The Nicene and Post-Nicene Fathers. Grand Rapids: Wm. B. Eerdmans Publishing Company, 1979. Vol. I, pp. 644-5). Constantine did not mention the Sabbath at all in this edict. He only recognized the first day of the week as the church’s day.
We see from the above sources that the keeping of the Lord’s Day began from the time of the apostles and the church fathers. This has been the practice throughout the ages.