The first century church account took the communion on the first day of the week. Didache recorded it.I'm unaware that the Didache records that the first century church took the communion on the first day of the week. Could you provide a reference, please?
I am aware that the Didache records that the first century church took the communion on "the Lord's day" (14:1 - http://www.paracletepress.com/didache.html), but it's an assumption that "the Lord's day" refers to the first day of the week. It probably so refers, but it is an assumption. (A decent case can be made from scripture (not post-scripture writings) that "the Lord's day" refers to the Sabbath; I don't believe that's the case, but the point is that "the Lord's day" simply isn't defined by scripture; we make assumptions as to what it means.)
The Didache also tells us we should fast on Wednesdays and Fridays (8:1); this is obviously adding to God's word, as there is no Biblical command to do this, just as there is no Biblical command to eat the Lord's Supper on any particular day. To insist there is such a command, or to appeal to post-Biblical writings to insist there is such a command, is to add to God's word just as surely as commanding fasting on Wednesdays and Fridays.
Regardless of what the practice was in 40 A.D., or 70 A.D. or 99 A.D., or 325 A.D., the Bible simply never makes a command to eat the Lord's Supper with any particular frequency on any particular day at any particular time of the day in any particular manner. The best we have in the Biblical text is:
- the inauguration, which took place in the midst of a full-blown meal which took place annually, at night-time, re-purposing some of the elements of that meal (Mark 14:, esp v. 12, 17, 22-25)
- a hint of daily eating (Acts 2:42, 46)
- another eating, probably daily (otherwise how would it help the needy?), again taking place in the midst of a full-blown meal, probably at night-time, which also served as a "feed the needy" meal, with no mention of singing or giving, which Paul says wasn't really the Lord's Supper because they weren't waiting for one another before stuffing their own faces (1 Cor 11:17-34).
- a hint of possibly weekly observance at night-time either on a Saturday or Sunday pre-midnight evening or on a Sunday or Monday post-midnight, pre-dawn morning as part of an all-nighter assembly, with no mention of singing or giving (Acts 20:7-12).
Some people also try to marry 1 Cor 16:2's reference to "the first day" as being indicative of the disciples meeting on this day, which may be true, but is not certain; another likely possibility is that Paul is referring to the Roman Market Day, when the population went grocery shopping, and when it would make sense to "lay by him in store" (putting in storage, not putting into a church treasury for paying the church salaries/bills) a portion of your funds, not for groceries, but for the year-long collection being made for the poor saints back in Jerusalem.
MacMullen (http://www.jstor.org/stable/1087739?seq=9#page_scan_tab_contents) writes about the Roman Market Days in Italy:
What is certain from the evidence, however, is the importance and completeness of the arrangements developed in this section of Italy for the exchange of goods between the rural population on the one hand, and urban and itinerant merchants on the other hand. Efficiency required that they be brought together in large numbers, whether once every seven, or eight, or fourteen, or thirty days, or less frequently still. To this end a variety of other purposes were adopted: assemblies of worship, spectacles and entertainments, elections, or assizes. We may assume throughout the empire such successful answers to the demands of commerce as can be seen so clearly on the map of Campania.
In other words, there were regular market days, presumably not just in Italy but throughout the empire, which were not only for buying groceries but also provided an opportunity for regular worship assemblies to arise.
Less authoritative, Wikipedia (https://en.wikipedia.org/wiki/Roman_calendar#Nundinal_cycle) also speaks of the Roman Market Day:
The Romans of the Republic, like the Etruscans, used a "market week" of eight days, marked as A to H in the calendar. A nundinum was the market day; ... The nundinal cycle formed one rhythm of day-to-day Roman life; the market day was the day when country people would come to the city, and the day when city people would buy their eight days' worth of groceries. ... The nundinal cycle was eventually replaced by the modern seven-day week, which first came into use in Italy during the early imperial period, after the Julian calendar had come into effect in 45 BC. The system of nundinal letters was also adapted for the week. For a while, the week and the nundinal cycle coexisted, but by the time the week was officially adopted by Constantine in AD 321, the nundinal cycle had fallen out of use.
And as mentioned above, there is the assumption that the phrase "Lord's day" refers to the first day of the week, but also as mentioned, that's just an assumption, with no Biblical evidence whatsoever to support it, and in fact, is in contrast with the general Biblical usage of the Sabbath as being the "day of the Lord", as in Isa 58:13:
If you turn back your foot from the Sabbath,
from doing your pleasure on my holy day,
and call the Sabbath a delight
and the holy day of the Lord honorable;
if you honor it, not going your own ways,
or seeking your own pleasure, or talking idly;