In the early years of the church, public worship was engrafted and modeled on the order of synagogue services. It consisted of the following elements, not necessarily in this order:
1. Preaching (Matt. 28:20; Acts 20:7; 1 Cor.14:19, 29-36).
2. Reading of Scripture (James 1:22; Col.4:16; 1 Thess.5:27; Acts 13:15).
3. Prayer (1 Cor.14:14; 16).
4. Singing (Eph.5:19; Col.3:16; Eph.5:14; 1 Tim.3:16).
5. Administering the Ordinances of Baptism and the Lord’s Supper (Matt.28:19; Acts2:41; 1 Cor.11:18-34).
6. Almsgiving (1 Cor.16:1-2).
The Christians in Paul’s time seem to have regarded the Lord’s Day (Sunday) rather than the Jewish Sabbath (Saturday) as the day on which they were accustomed to assemble together to break bread (Acts 20:7) and the day on which Christians were to lay aside money which they wished to donate for charitable purposes (1 Cor.16:2).
Because the first day of the week was the day on which Jesus rose from the dead and appeared to his disciples (Matt.28:1-15; Mark 16:1-14; Luke 24:13-49; and John 20:1-26), and Pentecost fell on the first day in which the church was born and the Holy Spirit given to indwell the saints (Lev.23:11,15; Acts 2:1), it became customary for many congregations to assemble for worship on the Lord’s Day.
Ignatius, the church father who was born during the time of Jesus’ ministry, was a disciple of the apostle John, said this about the Sabbath–“If, therefore, those who were brought up in the ancient order of things 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 — whom some deny, by which mystery we have obtained faith . . (Epistle to the Magnesians, chapter 9).
The disciple of Polycarp, Justin Martyr, wrote:
And we afterwards continually remind each other of these things. And the wealthy among us help the needy; and we always keep together; and for all things wherewith we are supplied, we bless the Maker of all through His Son Jesus Christ, and through the Holy Spirit.
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 succors 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(Comments on weekly worship from chapter 67 of First Apology).
It should be noted that some members of the early church made no distinction between days of the week, Jewish festivals, Sabbaths or even the Lord’s Day, esteeming every day alike. These were not judged or held in contempt, since they were acting out of their fear of God (Rom.14:5). Some of the Jewish Christians continued to keep the seventh day Sabbath and the Jewish festivals, which was seen as a matter of Christian liberty (Col.2:16) providing these believers did not regard the observance as necessary to salvation (Gal.5:2).