Actually, Sabbath is any of the seven days in a week specifically set aside for the LORD.
The Jews would kill you if you reasoned like that. The Jesus was crucified is known as the day of preparation, the day he layed on the tomb known as the Sabbath day, and the day he resurrected is agreed to have been on the first day. These days could not have been any day (see Luke 23).
For all we know, Yahshua might have been crucified on Saturday. It is impossible to pin the exact date in time he died let alone figure out what day it was. Try lookin at Sabbath from my point of view.
Genesis 2 doesnt say that YHWH started countin from Monday or frm Sunday or wotevr, it just sez the seventh day.
You will need to understand that there was a specific day when God said, let there be light, and it was so...and the evening and the morning were the first day. The process continued until the sixth day, and on the Seventh day God rested and that's why the Sabbath commandment is tied to memory of creation. Unless you can prove that the first day was anyday of the week; meaning if you can prove that the day God said let be light was equally as Tuesday as it was Friday, your argument cannot hold. Or is the numbering of days in Genesis 1 from 1 to 7 is insignificant?
Yes there was a specific day YHWH said let there be light, it was actually the first day as in the VERY FIRST DAY. (Why would YHWH start creation on a Monday -the hangover day- when Sunday would have been more fitting? 
) And as I said before, no one can prove beyond reasonable doubt what day the first day of the week was and that is my argument. U'll find that it holds as much water as the earth did on the day before day one...
Y is this relevant?
It is the only way to worship God as the creator.
I thought that the only way to worship YHWH was in Spirit and in truth?
Tha seal of the LORD. The most important commandment. It is stil whole n branded on those who set aside any one day (whether SDA, Christian or Islam etc) for the worship of the LORD.
Those who worship on Sunday dont brand the word Sabbath on themselves. On the contrary, they admit that the Jews Sabbath falls on Saturday but Jesus' resurrection on Sunday mandates them to commune on the Lord's day.
The only reason Protestants and their like dont exactly call Sunday Sabbath is cz it would spark friction amongst other believers about who is right & who is wrong, defeatin the whole purpose of worshippin...going to heaven. However, u will find that Protestants and their like treat Sunday as their Sabbath and indeed believe Sunday is Sabbath. Furthermore, we all know that its the Papal office who seeked to change times n seasons when they changed the day of worship to sunday officially but who's to say that that day had not been changed before. Why were Pagans worshippin on Sunday? Cz it was called Sun day? Dint pagan worship spring in defiance 2 true worship back then as it does these days? Was it not a day they wud worship alongside true worshippers so that they seem to b on the right track? History repeats itself tirelessly over n over, just how many times it does repeat itself, we arent sure.