The first paragraph is quoting my words. Therefore, I will reply. The alternative translation of Romans 14:5 would be;
One man esteems one day above another: another esteems every day. Let every man be fully persuaded in his own mind.
The Jews knew full well that the Sabbath Day was far more important than any of the other six working days because they knew Yahweh Himself made it to be different and more important than the others. He did that by sanctifying the 7th day, putting His blessing only upon that day, and commanding men to keep it holy. Fast days, Purim, Chanukah, etc., do not come close to the importance of the 7th day Sabbath.
By reading the Sabbath into this verse, it leads us to believe that some believers in Paul's day considered the Sabbath no different from any other day. That, then, leads to the mistaken belief that there were some believers that didn't "regard" the Sabbath Day at all (verse 6). By not reading the Sabbath into this verse, it leads us to believe the more likely scenario that no one in that day would consider the Sabbath to be like a common workday. Especially after Yeshua taught us things like it being lawful to heal on the Sabbath, or pull an ox out of a ditch, or that the son of man is lord of the Sabbath; Or Paul's teaching that the law, including the Sabbath, has been firmly established; or Isaiah's prophecy that all flesh will worship Yahweh from one Sabbath to another in the new heavens and new earth (Isaiah 66:22-23).
You are correct that early Christians were worshiping on the Sabbath until they started being persecuted and that "
THEY" moved the special day to the first day (although your reference to Acts 2:46-47 says no such thing). Neither the Father, nor the Son, nor any Apostle gave a command to move the day. It was the choice of people trying to save their lives. Eventually, the practice became a deeply ingrained
tradition, so much so that now it is those who desire to restore the true Sabbath Day that are being persecuted by supposed believers. We are treated like lepers and called all sorts of names like "legalist", "old wine skins", "Pharisees", "fallen from grace". We are kicked out of churches and treated like pond scum. Why? Because we would rather obey Yahweh than man.
Paul did no such thing. He was admonishing believers to not allow anyone outside of the Body of Messiah to judge us. When he wrote, "Let no man judge you," he was referring to the deceivers of verses 4, 8, and 18 that were judging the Colossians regarding the things mentioned in verse 16. They had been imposing their man-made commandments and traditions upon the Colossians. Paul told them not to allow anyone to judge them concerning those matters. An important addition was made in the KJV that does not appear in any Greek manuscript. The word "is" in verse 17 was added, which changes the meaning of Paul's statement. That is why it is written in italics. Retaining the word "is" implies the thought of shadow vs. reality. In other words, Messiah fulfilled the shadow of the things mentioned in verse 16. However, if you remove the added word "is", it implies that we should not let any man outside the body of Messiah judge us in respect to these things.
Let no man therefore judge you ... but the body of Messiah.
Indeed that is in line with the context of Paul's previous statements. Notice Col.1:18 & 24 and Col.2:19, all of which teach us that the body of Messiah is the church or all true believers.
Verse 17 states that these things "are" a shadow of things "to come" not that they "were" a shadow that was now fulfilled. Paul wrote this epistle approximately 30 years after Messiah's death and resurrection and yet he still spoke of them as unfulfilled shadows of something in the future.
According to Jeremiah 31:33, it was the "Torah" (not some new law that includes a Sunday sabbath) that would be written on the hearts of New Covenant believers. All Israel understood what "Torah" was. They knew the already existing Torah of Yahweh would be written on their hearts.