<P> The phrase the "Lord's Day" appears only once in the Bible in Revelation 1: 10 which was written near the end of the first century . It is the English translation of the koine Greek kyriake hemera . The adjective kyriake ("Lord's") often elided its noun, as in the neuter kyriakon for "Lord's (assembly)", the predecessor of the word "church"; the noun was to be supplied by context . </P> <P> In Rev. 1: 10, the apostle John, used kyriake hemera ("I was in the Spirit on the Lord's Day") in a way apparently familiar to his readers . Observers of first - day worship hold that this means he was worshiping on Sunday, resurrection day . Seventh - day Sabbatarians hold that since Jesus said he was "Lord of the Sabbath" and that Isaiah called the Sabbath the "Lord's Holy Day" then the Lord's Day is the Seventh - day Sabbath (i.e. Saturday). Both parties accordingly use this verse to lay claim to the name "Lord's Day" for their day of worship. mark 2: 28 </P> <P> The New Testament also uses the phrase te mia ton sabbaton ("the first day of the week") both for the early morning (Mary Magdalene John 20: 1) and evening (the disciples in John 2: 19) of Resurrection Sunday, as well as for the breaking of bread at Troas (Acts 20: 7) and the day for the collection at Corinth (1 Co 16: 2). </P> <P> The term "Lord's" appears in The Teaching of the Twelve Apostles or Didache, a document dated between 70 and 120 . Didache 14: 1a is translated by Roberts as, "But every Lord's day gather yourselves together, and break bread, and give thanksgiving"; another translation begins, "On the Lord's own day". The first clause in Greek, "κατά κυριακήν δέ κυρίου", literally means "On the Lord's of the Lord", a unique and unexplained double possessive, and translators supply the elided noun, e.g., "day" (ἡμέρα hemera), "commandment" (from the immediately prior verse 13: 7), or "doctrine". This is one of two early extrabiblical Christian uses of "κυριακήν" where it does not clearly refer to Sunday because textual readings have given rise to questions of proper translation . Breaking bread (daily or weekly) may refer to Christian fellowship, agape feasts, or Eucharist (cf . Acts 2: 42, 20: 7). Didache 14 was apparently understood by the writers of the Didascalia and Apostolic Constitutions as a reference to Sunday worship . </P>

When did the christian church start worshipping on sunday