Upvote:1
The Sabbath will always be Friday evening to Saturday evening since it is defined by being the seventh day (the very root of the word is seven).
"The Lord's day" is almost certainly Sunday (based on the day of the resurrection) though it is not exclusively so in all sources.
See my answer to the related question but it is a bit simplistic to say that the disciples started meeting on Sundays, since they met every day! See the other answer of that question for scriptural evidence that it is not important what you choose to do on which days, but "let every man be fully persuaded in his own mind".
Upvote:1
Since the disciples spent the previous 3 1/2 years living together they were often gathered on a daily basis. It is not unusual or special that they were together on the 1st day of the week or any other. Saying the Sabbath (which means seven) has now switched to sunday (which is the first day) because they were together is quite a stretch.
There are many verses that specify the Sabbath as the seventh day of the week and others that show examples of what is right and wrong, (work six days rest on the seventh, etc.).
To answer the question can the 7th day be any day of the week, well...The Hebrews counted their days, they didn't name them. So when it says to honor the Sabbath on the seventh day that is the name of the day. The Messiah also honored the Sabbath and taught how to observe it, and he too observed the Sabbath on the 7th day. It is pretty important too since it is the only sign between Our Father in Heaven and His children throughout our generations, see Exodus 31.
As for Communion it originated from the instructions the Messiah gave concerning the Passover meal. It does not relate to any of the Biblical instructions given on how to observe the weekly Sabbath.
Upvote:2
There is a situation where honoring the Sabbath would be difficult to do on any day besides Sunday. The conditions are:
If you don't fit those two conditions then its difficult to find biblical support against moving the Sabbath day around.
However, I would never personally do it. Besides the fact that I fit the two conditions described above, I would feel like I was saying, "The happenings of my life are of a higher priority than the Kingdom of God" (See Matthew 6:33). But that's just me. I know that's not your intention and its great that you strive to honor the Sabbath once a week.
Upvote:5
In Genesis 2:2-3 (NIV) it says,
2 By the seventh day God had finished the work he had been doing; so on the seventh day he rested from all his work. 3 Then God blessed the seventh day and made it holy, because on it he rested from all the work of creating that he had done.
It would seem to indicate only the existence of 'a day of rest', but there is no reference to a certain day of the week being more deserving of said title. I only see evidence that we should observe 'a day of rest'; though whatever day of the week that might happen to be is of little to no consequence really.