#1. God said that "He sanctified it" in Genesis 2:3 making it a Holy day.
#2. God said that "He rested -- therefore He sanctified, blessed and made it holy" speaking of that Genesis week in summary.
Still, that is viewd in retrospect from the Mosaic period. Really, every day is holy, or is God's presence not in any other day, as Armstrong says? He sanctified many things that were apart of the Law that are not still in effecxt (the Temple, etc). Blessed and sanctified do not equal "commanded all men to oberve it for all times".
#3. God did not "write a command to Cain not to murder" but mankind was still obligated by that law and it was still a "sin" for Cain to murder.
That's apart of the universal laws, which were always commanded to all men, and are written in man's conscience. The Sabbath never had that status, but was always for Israel's identity.
#4. Christ said "The Sabbath was MADE for mankind and not mankind MADE for the Sabbath" speaking of the making of both. There is no hiding the fact that the 7th-day memorial of creation week was given in Gen 2:3 on the 7th day of creation week. In fact - that is the only thing that marks that 7th day of creation week. Hence our 7-day week.
Once again, this says nothing about a universal eternal command to refrain from work that day every week.
#5. There is no place in scripture saying that the Holy Spirit is given in place of the Creator's 7th-day memorial of creation - made "for mankind" as a holy day in Gen 2:3.
In John 3 Christ states that the -pre-cross Jewish bible teacher "must already know" that it is "already a fact" that one must be "born of the spirit" to enter the kindgom of heaven. The Holy Spirit was not "optional" to the Gospel or salvation. The list of saints given in Heb 11 - are those born again by the Holy Spirit.
In the Calvinist debate, didn't you agree with most of the other non-Calvinists that the Spirit was not given before Christ? (Since that was the Calvinists' only way to have salvation in the Old Testament if the new birth precedes belief.) The Spirit was given to the prophets for inspiration, but there was no regeneration. Else, that dispensation would have been sufficient. Christ was telling Nicodemus the way it should be, but the whole point was that things weren't working they way they should. That's why Christ came in the first place.
The Isaiah 66 statement about the New Heavens and New Earth - shows the "eternal" scope of the Creator's memorial of creation -
Continuing with the last point, this was conditional on the Israelites fulfilling their purpose of "declar[ing] My glory among the Gentiles"(v.19). In other words, there would have been no Christ dying, no new dispensation, so the whole Law would have been still in effect. Notice, the new moons (v.23) and the offerings(v.20) are mentioned as well! Even if one takes the theory that the Law will be reinstituted, (and why would sacrifices ever be reinstituted, for eternity, yet, after Christ's work is finished?) still, we do not keep those other two points of the Law, so we cannot use this to say that the Sabbath is "eternal" either.
Then - as you point out - possibly our Creator was "having a bad idea" when He "made the 7th day of creation week - a holy day" in Gen 2:3.
After all why should it be a "blessing for mankind" to obey God? Why should showing love for God and love for our neighbor in anyway "bless mankind"? Perhaps you do have a point there.
Not a bad idea, just a temporary
"blessing" that is fulfilled by Christ.
No question that God Himself can choose to explicitly "sanctify, bless and make holy" any other day He chooses. But He has not.
Whether that day could "also serve as a memorial of creation of mankind" as we find in Gen 2:3 and Exodus 20:8-11 by virtue of the fact that the Creator chose to add it to creation week, to rest on that day and to set an example for mankind - remains to be seen.
Once again, not arguing for another day. But the advocates for Sunday use similar arguments as you: indirect implication and "everybody must have known", as in the quote from the link s.phoenix posted above:
"The day was transferred from the seventh to the first day of the week, not on the ground of a particular command, but by the free spirit of the gospel and by the power of certain great facts which he at the foundation of the Christian church. It was on that day that Christ rose from the dead; that he appeared to Mary, the disciples of Emmaus, and the assembled apostles; that he poured out his Spirit and founded the church;690 and that he revealed to his beloved disciple the mysteries of the future. Hence, the first day was already in the apostolic age honorably designated as "the Lord’s Day." On that day Paul met with the disciples at Troas and preached till midnight. On that day he ordered the Galatian and Corinthian Christians to make, no doubt in connection with divine service, their weekly contributions to charitable objects according to their ability. It appears, therefore, from the New Testament itself, that Sunday was observed as a day of worship, and in special commemoration of the Resurrection, whereby the work of redemption was finished.691
The universal and uncontradicted Sunday observance in the second century can only be explained by the fact that it had its roots in apostolic practice. Such observance is the more to be appreciated as it had no support in civil legislation before the age of Constantine, and must have been connected with many inconveniences, considering the lowly social condition of the majority of Christians and their dependence upon their heathen masters and employers. Sunday thus became, by an easy and natural transformation, the Christian Sabbath or weekly day of rest, at once answering the typical import of the Jewish Sabbath, and itself forming in turn a type of the eternal rest of the people of God in the heavenly Canaan.692 In the gospel dispensation the Sabbath is not a degradation, but an elevation, of the week days to a higher plane, looking to the consecration of all time and all work. It is not a legal ceremonial bondage, but rather a precious gift of grace, a privilege, a holy rest in God in the midst of the unrest of the world, a day of spiritual refreshing in communion with God and in the fellowship of the saints, a foretaste and pledge of the never-ending Sabbath in heaven."
In light of this:
That God was giving mankind the 7th-day memorial of His creative act in Gen 2:3 - as a prediction of the destruction of the world and making of a new World (something that has not yet happened) - does not appear to fit.
As the quote says, (And I forgot to mention), the Sabbath was also a shadow of the milennial rest. As you know, the original creation week was a type of the ages of mankind, so the sabbath prefigured the Milennium.
