The word “sabbath” comes from Hebrew, and it denotes the holy, designated day of rest during the week. The Bible, in the book of Exodus, commands that the faithful not forget the sabbath day such that it remains sacred to them.
In traditional Christian culture, the sabbath worship-day occurs on Sunday, but in the Jewish tradition, the sabbath occurs every Saturday. Why, considering the shared heritage between Judaism and Christianity, do the sabbath days differ?
It appears that the ancient Christian church saw the observance of the sabbath on a Saturday in the same way that they saw acts of circumcision, which were compulsory in Judaism. The early Church fathers held that traditions like circumcision were not binding on Christians, and they felt similarly about the Saturday sabbath, opting instead to worship on the eighth day, or Sunday, which they called the “Lord’s day.”
Evidence of this shift can be found in writings from ancient church authorities. For example, the Letter of Barnabas, written by an apostolic father as late as 130 AD, relates how the community worshiped joyfully on the “eighth day” and justifies this in that it is the day that Jesus was resurrected.