Curious "musing". There is little to suggest from the writings of Church history that such was ever the view. In fact, the quote from Barnabas you gave seems to teach something quite different, for Barnabas concludes:
I will make the beginning of the eighth day which is the beginning of another world. Wherefore also we keep the eighth day for rejoicing, in the which also Jesus rose from the dead, and having been manifested ascended into the heavens.It was the eighth day, i.e., the Lords Day, that was significant to the early Church. There is no mention here a literal "thousand years" on the earth as a Sabbath. So there was really nothing for them to loose. The true rest for Gods people is in the new heavens and new earth wherein righteousness dwells.
Hebrews 4 explains the rest of God for His people, and it has nothing to do with the so-called future "thousand years".
Please reread the entire chapter 15 quoted in my post. There are 7,000 years (7 days) appointed to Adamic man. The last 1,000 years (7th day) is the Sabbath.
After the 7th day or 7000 years is the 8th day the new heaven and new earth - a time of not counting.
The belief appears again in chapter 33 of 2 Enoch (not to be confused with 1 Enoch) - which has been dated between the 1st century B.C. to the 10th century A.D. but most often, late 1st century A.D.
I do not.