You cannot say that in good conscience, because the early Christians in the apostolic churches worshiped on the first day of the week (the eighth day). Read your New Testament again (and very carefully). And that practice has continued for over 2,000 years. It is only since the 19th century that Sabbatarianism has come into play, and only in certain groups which mix the Old and New covenants.
Evidently you cannot see the tremendous difference that the death, burial, and resurrection of Christ made to man's relationship with God. Neither can you see the significance of the LORD'S DAY (which is the first day of the week and the morrow after the sabbath). Neither can you see the significance of the fulfillment of the feasts of First Fruits and Pentecost. Both were on the first day of the week.
Furthermore, the Torah makes it perfectly clear that the 7th day sabbath was given to Israel under the Old Covenant. But under the New Covenant sabbaths are shadows of the reality -- which is Christ.
Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the sabbath [days]: Which are a shadow of things to come; but the body is of Christ. (Col 2:16,17)
This tells us that the Lord Jesus Christ Himself is our Sabbath -- our eternal rest. We rest in Him because He has done everything for us, and we have entered into God's rest.
For we which have believed do enter into rest, as he said, As I have sworn in my wrath, if they shall enter into my rest: although the works were finished from the foundation of the world. For he spake in a certain place of the seventh day on this wise, And God did rest the seventh day from all his works. And in this place again, If they shall enter into my rest. (Heb 4:3-5).
When Jesus said that He was Lord of the Sabbath, He had all these things in mind already. As Lord of the Sabbath, it is He who determines the Christian Sabbath.