I presented Romans 14, and there are several Scriptures which speak of the early Christian (Jewish and gentile) church communing on "the first day of the week. So far,
you have not presented one single Scripture verse.
if that is the case why change from the Sabbath that God established to a different one?
The Sabbath is God's day of rest. If any gentile sought salvation pre-Christ, he went in through the Covenant of Moses. If any gentile sought salvation post-Christ he has to go in through the New Covenant. Were or are you a Jew who was present at the foott of Mt. Sinai or a descendent of one who was? If you are going to keep the Sabbath and argue that it can only be the last day of the week because that's how the Jews do it... well, then are you: removing your chametz on the Eve of Passover (Ex. 12:15)? are you fasting on Yom Kippur (Lev. 23:27)? are you mixing garments made of wool and linen together (Deut. 22:11)? Because if you are or are not, you have broken a mitzvot(s) and need to seek forgiveness when Yom Kippur comes around!
If you are going to follow the Covenant of Moses then you are going to have to obey all 613 mitzvots.
James 2:13
For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all.
Only those who attend A Church can speak of God? Do you make them dress smartly too?
You identify yourself as a "non-Christian" and isolate yourself from the Christian community by not going to church (the banana that gets separated from the bunch gets pulled and eaten. see 1 Peter 5:8), yet somehow I'm to take your words at face value? :eeeekkk
is it my opinion/interpretation?
Yes, it's your opinion. You have not yet provided one Scripture verse to determine Christians must keep the Sabbath on Saturday.
God commanded the Sabbath when writing it with his finger,
Christians give a day to honor God, and most keep it on Sunday. However, there are several Christians who keep it on Monday, Tuesday, Wednesday...etc. I know of a nurse who works in the ER who keeps the Sabbath on Wednesday. She is honoring God, and keeping the spirit of the command. What is the point of keeping the Sabbath on Saturday, if one is not going to honor God or is keeping it for the sake of self-righteousness so that others can see how "holy" one is?
the nation kept the same Sabbath,
If you want to be included with those who had heaven and earth testify that they will obey God's commands through the Covenant of Moses...well, okay. But, don't forget--
that same nation broke their Covenant with God.
Jesus kept the same Sabbath,
Jesus was a Jew who did not break a single mitzvoh.
His disciples kept the same Sabbath,
His disciples were Jewish.
the first followers kept the same Sabbath
They first followers also met on the first day of the week.
Acts 20:7 (NIV)
On the first day of the week we came together to break bread. Paul spoke to the people and, because he intended to leave the next day, kept on talking until midnight.
the Jews keep the same Sabbath.
The Jews are under the Covenant of Moses, and the Jews today are in violation of the Covenant because they do not follow all 613 mitzvohs.
Todays Christians don't!.. so someone somewhere once started another Sabbath..it may not matter at all but its interesting to find out why if it meant so much to God in the first instance and why we do what we do today.
Colossians 2:16-17 (NIV)
Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day. These are a shadow of the things that were to come; the reality, however, is found in Christ.
Galatians 4:8-10 (NLT)
So now that you know God (or should I say, now that God knows you), why do you want to go back again and become slaves once more to the weak and useless spiritual principles of this world? You are trying to earn favor with God by observing certain days or months or seasons or years.