Oh gosh, where to start?
I don't think "The Lord's Day" has any singular definition in scripture. I think squeezing the NT usage into one single prophetic usage seems a little out of context.
"The day of the LORD" was used in the Tanach as a reference to end time events. "The Lord's Day".... the same phrase written in reverse order but that doesn't alter any meaning here... appears on time in the NT and that in a book discussing prophesy, mostly end time. The man who wrote it was having a vision ("I was in the spirit on the Lord's day...") and thus I think it is out of context and squeezing the meaning to assume it means a "day of the week" when the use of "Lord's Day" doesn't appear in external writings until ABOUT the middle of the 2nd century.
Furthermore, the testimony of the early Christians is in tandem with the traditional understanding, and the idea that it is purely a reference to the prophetic end-times I have yet to see taught by the ancients. Please understand that I put ancient consensus way above modern speculations and assertions. They decided on and gave us the canon after all.
The NT wasn't compiled and canonized until 200AD (ish) and by then "Lord's Day" was well in use and meaning SUNDAY, actually... that word didn't even exist then... but it meant the 1st day of the week. However, that isn't how it was used in Scripture, that use came about when after Yeshua resurrected on the first day of the week, a SMALL amount of Jewish believers saw that as a sign and set that day apart ALSO. However, the "also" got lost when, after the bar Khokba revolt and the Greeks began to be the majority face of the faith, they gravitated toward the first day and the perceived sign it represented and within 20 years of the bar Khokba revolt, more "Christians" were keeping Sunday over Saturday. But, there is no Scriptural mandate to move the Sabbath, there is no Scriptural mandate calling a day of the week by the already known phrase, "The Lord's day." It had a prophetic meaning and it also had a religious CULTURAL meaning and the church has been following the cultural meaning since then. I don't... and while I respect your views I won't change. Yeshua kept the 7th and he is the model I believe we are to follow.
Secondly, the Council of Laodicea is not an ecumenical council. It was only a local council.
Agreed, I should not have used this as my example. What I should have used was the Constantine decree of making Sunday the legal day of worship. That said, while you are correct that the Council of Laodicea was a local Council... it's decrees are exalted by the church to this day and you know that. It is counted among the early Christian writings and carry as much weight as any early Council.
In other words, when a part of the church starts to create a new doctrine around what is clearly adiaphora (eg. Rom. 14 type things) then the ancients would often make a halachic ruling that strengthened the opposite position. In this case, clearly some people had begun to teach that the only legal time to worship God was on the Sabbath, thus violating the authority of Christ and the scriptures. The response was rather an example of Newton's law- the action created an equal but opposite reaction- Sabbath keeping was ruled out in protection of the principles outlined in the scriptures eg Rom 14. Both positions equally wrong. However, the canons of Laodicea were never regarded as either universally binding or infallible dogma. Nor can it be proven that they bring in a new theological innovation. Only half-witted modern "scholars" make such absurd and baseless assertions. Those modern spirits have a lot of influence in the Messianic movement, sadly.
We don't see Romans 14 the same at all. I see Paul understanding that within the ranks there were many other fasts and days set apart, in addition to his understanding where others came from and what foods they used and did not use... and he is saying that if you want to keep the The Fast of Gedaliah or desire to set the day of Purim aside, you can but what you can't do is make that a decree over all. That is what Romans 14:1 is saying.... you can receive into the faith those who do these things but NOT until a doubtful disputation or as Strong's defines the last word, "judicial estimation." So it is NOT a verse to use to validate church decree, it is specifically saying the opposite.
Blessings.
Ken