The Sabbath predates the Jewish law and was given to all of creation in Gen 2:3. Isaiah prophecies about the Sabbath post the coming of the Messiah suggesting God is not finished with it yet.
Perhaps we get modern church meetings and the Sabbath confused, the early church met daily, we in general meet once a week and regard it as keeping the Sabbath because we went to church..
ISAIAH 66: By teaching that Isaiah 66:23 proves that the weekly Sabbath will be kept throughout eternity, Seventh-day Adventists err by not teaching the same about the new moon Sabbaths. They ignore the context of Isaiah 66.
66:1-3 destroys the SDA doctrine that God lives in a literal temple patterned after that given to Moses for Israel.
6:10-14 destroys the SDA doctrine that literal Israel and Jerusalem are no longer involved in future prophecy and special God's love.
6:17 refers to unsaved persons attempting to save (sanctify) themselves using methods opposite to that what God teaches.
6:19-21 prophesizes a final gathering of all nations to Jerusalem which is totally ignored in SDA prophecy.
6:22 describes the literal Messianic reign of Christ on earth in terms of "new heavens and the new earth." This is more of a problem text for SDAs than others because they deny a literal Messianic reign of Christ on earth.
6:23 means "every day of the month" and "every day of the week" -- from one month to another; from one week to the next. If (as SDAs insist) 6:23 proves that the weekly Sabbath will be observed throughout eternity, it proves too much because it would also prove that the monthly Sabbath will be also (and SDAs do not teach that).
6:24 disproves the SDA doctrine of annihilation. It also places the events of Isaiah 66 during the Messianic reign on earth (the Millennium) and not following Revelation 21:4.
Rev 21:25 suggests that there will be no days and nights in the new Jerusalem --therefore no divisions of days
SDAs quote none of the texts surrounding 66:23 because their own theology denies both a literal restoration of Israel in the last days and/or any attempt to reconcile the texts in their own eschatological context. While quoting it to convince others, none of it makes sense in their own eschatology.
The Sabbath Has Benn Changed Many Times