Romans 14:5
One person esteems one day as better than another, while another esteems all days alike. Each one should be fully convinced in his own mind.
Although I have been keeping actual Sabbath more often, I also attended services on Tuesday and Sunday.
If we want to get technical we better get our Friday night sunset countdown game on too
Rom 14 has an "inserted word" the word "alike" as almost every Bible translation will indicate to its readers via the italics.
The actual text says "while another esteems EVERY day." Then the text says that by "esteem" it means "observe" - - "the one who OBSERVES the day observes it unto the Lord .. the one who does not OBSERVE the day does so unto the Lord" -- Rom 14 speaking of the Lev 23 annual holy days.
By contrast in Galatians 4 - Paul condemns the "observance" of even ONE of the pagan days.
In the OT Isaiah 66:23 states explicitly that the Sabbath applies to "
All mankind" in Is 66:23
In Gen 2:1-3 the Sabbath applies to "All mankind" --
Adam and Eve.
In Mark 2:27 the Sabbath applies to "All mankind" -- "
The Sabbath was made for mankind"
In Rev 14:7 it is all mankind that is called to worship God who "
created the heavens and the earth the seas and the springs of water" - a quote from the Sabbath commandment
in Heb 4 "
There remains therefore a Sabbath rest for the people God" actually quotes the Sabbath Commandment and says it 'remains' just as it was in Psalms 95.
In Rev 14:12 the saints
"KEEP the commandments of God and their faith in Jesus".
In 56:1-8 the Gentiles are singled out and specifically blessed for keeping the weekly Sabbath.
James 2 points specifically to the TEN Commandments and says that the common element that would make us "guilty of all" is based on "He who said" -- and as it turns out God said all ten of them not just nine.
In Eph 6:2 - the entire unit of TEN is being identified when the text says "Honor thy father and mother for this is the FIRST commandment with a promise" -- that requires a specific unit of Law -- and is only true of the TEN.
Ex 20:8-11 it is
BOTH Israel AND the gentile that "stays within their gates" that is bound to keep the Sabbath.
In Acts 18:4
both Gentiles AND Jews are worshiping "every Sabbath" so also in Acts 17:1-4 so also in Acts 13.
In your own statement you admit that the Jews would have known that the TEN Commandments - including the 4th Commandment were included in the "LAW of God" - so then when Jeremiah says that the NEW Covenant includes God writing His "LAW on our heart and mind" both Jeremiah and HIS readers would have known that it was sin to violate the Sabbath and that the 4th Commandment was included in God's moral LAW