Primary Source Testimony of Early Sunday Worship

But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: Exodus 20:10

"The following are all the hints respecting the nature of first-day observance during the first three centuries. 

Justin Martyr

The epistle falsely ascribed to Barnabas simply says: "We keep the eighth day with joyfulness."
Justin Martyr describes the kind of meeting which they held at Rome and in that vicinity on that day, and this is all that he connects with its observance.
Irenaeus taught that to commemorate the resurrection, the knee must not be bent on that day, and mentions nothing else as essential to its honor. This act of standing in prayer was a symbol of the resurrection, which was to be celebrated only on that day, as he held.

Bardesanes the Gnostic represents the Christians as everywhere meeting for worship on that day, but he does not describe that worship, and he gives no other honor to the day.


Tertullian

Tertullian describes Sunday observance as follows: "We devote Sunday to rejoicing," and he adds, "We have some resemblance to those of you who devote the day of Saturn to ease and luxury."
In another work he gives us a further idea of the festive character of Sunday.
Thus he says to his brethren: "If any indulgence is to be granted to the flesh, you have it. I will not say your own days, but more too; for to the heathens each festive day occurs but once annually; you have a festive day every eighth day."
Dr. Heylyn spoke the truth when he said:

"Tertullian tells us that they did devote the Sunday partly unto mirth and recreation, not to devotion altogether; when in a hundred years after Tertullian's time there was no law or constitution to restrain men from labor on this day in the Christian church."

The Sunday festival in Tertullian's time was not like the modern first-day Sabbath, but was essentially the German festival of Sunday, a day for worship and for recreation, and one on which labor was not sinful. 


But Tertullian speaks further respecting Sunday observance, and the words now to be quoted have been used as proof that labor on that day was counted sinful. This is the only statement that can be found prior to Constantine's Sunday law that has such an appearance, and the proof is decisive that such was not its meaning. Here are his words:


Irenaeus

"We, however (just as we have received), only on the day of the Lord's resurrection, ought to guard, not only against kneeling, but every posture and office of solicitude, deferring even our businesses, lest we give any place to the devil. Similarly, too, in the period of Pentecost; which period we distinguish by the same solemnity of exultation."

He speaks of "deferring even our businesses;" but this does not necessarily imply anything more than its postponement during the hours devoted to religious services. It falls very far short of saying that labor on Sunday is a sin. But we will quote Tertullian's next mention of Sunday observance before noticing further the words last quoted. Thus he says:

"We count fasting or kneeling in worship on the Lord's day to be unlawful. We rejoice in the same privilege also from Easter to Whitsunday."

These two things, fasting and kneeling, are the only acts which the fathers set down as unlawful on Sunday, unless, indeed, mourning may be included by some in the list."
J.N. Andrews