The dichotomy of Sunday Sabbath vs. Saturday Sabbath is a false dichotomy. It is not one or the other, all days are Sabbath to the Christian.
The Sabbath as was observed under the Law is but a shadow of the Sabbath that was to come, the Sabbath of being in Christ. The old Sabbath brought no real rest, for the Sabbath was Law, the very observance of that Sabbath was a work, an observance of Law. Can one rest and work at the same time? No, so the Sabbath of the law was a Sabbath on some levels, but on the spiritual level it was as much a work of the Law as any other part of the Law.
To substitute Sunday for Saturday is to turn to another ordinance, one which cannot bring rest, for it is no more a true Sabbath than the Sabbath in the Law.
Christians are are not under the Law, we shouldn't substitute a new law for the old, we should honor God by doing as he would have us do. We are warned about placing ourselves back under law, Galatians 3:1-5 NET
(1) You foolish Galatians! Who has cast a spell on you? Before your eyes Jesus Christ was vividly portrayed as crucified!
(2) The only thing I want to learn from you is this: Did you receive the Spirit by doing the works of the law or by believing what you heard?
(3) Are you so foolish? Although you began with the Spirit, are you now trying to finish by human effort?
(4) Have you suffered so many things for nothing? if indeed it was for nothing.
(5) Does God then give you the Spirit and work miracles among you by your doing the works of the law or by your believing what you heard?
So plain yet people still hunger to be under law, Jesus didn't need to die to put us under the law, to pick law over his gospel does not honor him. Both those arguing for Saturday Sabbath and those for Sunday Sabbath are picking Law over Gospel.
Let us turn to Hebrews, the book written to those most likely to misunderstand the purpose of the Law and to believe that they needed to observe the Law to receive salvation.
Hebrews 4:1-16 NET
(1) Therefore we must be wary that, while the promise of entering his rest remains open, none of you may seem to have come short of it.
(2) For we had good news proclaimed to us just as they did. But the message they heard did them no good, since they did not join in with those who heard it in faith.
(3) For we who have believed enter that rest, as he has said, "As I swore in my anger, 'They will never enter my rest!' " And yet God's works were accomplished from the foundation of the world.
(4) For he has spoken somewhere about the seventh day in this way: "And God rested on the seventh day from all his works,"
(5) but to repeat the text cited earlier: "They will never enter my rest!"
(6) Therefore it remains for some to enter it, yet those to whom it was previously proclaimed did not enter because of disobedience.
(7) So God again ordains a certain day, "Today," speaking through David after so long a time, as in the words quoted before, "O, that today you would listen as he speaks! Do not harden your hearts."
(8) For if Joshua had given them rest, God would not have spoken afterward about another day.
(9) Consequently a Sabbath rest remains for the people of God.
(10) For the one who enters God's rest has also rested from his works, just as God did from his own works.
(11) Thus we must make every effort to enter that rest, so that no one may fall by following the same pattern of disobedience.
(12) For the word of God is living and active and sharper than any double-edged sword, piercing even to the point of dividing soul from spirit, and joints from marrow; it is able to judge the desires and thoughts of the heart.
(13) And no creature is hidden from God, but everything is naked and exposed to the eyes of him to whom we must render an account.
(14) Therefore since we have a great high priest who has passed through the heavens, Jesus the Son of God, let us hold fast to our confession.
(15) For we do not have a high priest incapable of sympathizing with our weaknesses, but one who has been tempted in every way just as we are, yet without sin.
(16) Therefore let us confidently approach the throne of grace to receive mercy and find grace whenever we need help.
Verse one starts out with a mystery, how could the Hebrews who faithfully observed the Sabbath fall short of God's rest? We start to receive the explanation in verse 3, those who believe enter the rest, as you read the next few verses, you see that the Hebrews never received the rest even though they observed the Sabbath.
Verse 7 is a key verse, it tells us the Sabbath day, it is "Today". Now does that mean that is only applies to whatever day of the week this verse was written? No, of course not, each and every day is a Sabbath day to the Christian. Saturday is, Sunday is, so are Monday, Tuesday, Wednesday, Thursday and Friday, those days are all Sabbath days.
Verses 8-10 tell us a rest remains, that we get to cease our labors, just as God ceased his. The old Sabbath would almost seem as if God got to the 8th day and started all over again with his labors. That would be how people freed from the Law through Jesus Christ who turn away from his works and once agains substitute their own unworthy works behave.
The rest of Chapter 10 is an exhortation on how to behave under our freedom from the law. We enter that rest given us by our Lord and we go to him, not the Law, to receive mercy and grace.
Man needs rest, to put him under a law, whether it is a law of Saturday Sabbaths or Sunday Sabbaths, steals that rest from him.
Marv