In Sunday: A History of the First Day from Babylonia to the Superbowl, Craig Harline traces Christian traditions and beliefs about Sunday. After a brief introduction to the origins of the seven-day week, he introduces the "Lord's Day." Early Christian Sunday practices were influenced by the Jewish Sabbath, and probably by the pagan Sun Day as well, writes Harline. But there is a range of opinion on exactly why they chose the first day of the week for communal worship. As Christianity gained prominence throughout the Mediterranean and Europe, celebrating Sunday as a special day became "nearly universal."
"Yet it wasn't merely the increased number of Christians that gave the Lord's Day its new stature between 300 and 800," writes Harline. " Just as important was the continued shaping of the day. This included adding 'rest' to the old tradition of 'worship' on the Lord's Day, continuing to formalize the day's worship, and the common use now by Christians of the very term 'Sun Day' [instead of 'the Lord's Day']."
Over time, the Sunday we know of formal worship services and (for most) a day off work, appeared on the horizon.
The trend toward a more visible Christianity, evident in the spread of literal rest on the Lord's Day, was also evident in changes in worship. In the first place, thanks to Christianity's official status after 392 and more free time than ever on the Lord's Day, worship became more public. Services began at midmorning now, rather than at inconvenient hours, and took place in clearly defined churches rather than in semi-secretive houses.
In the second place, worship on the Lord's Day became more formal. The elements and order of services were elaborated even further. Numerous brief statements of belief, or "creeds," ...1