The seventh day is used for many things such as the sign of the Old Covenant but it's also used to identify God's people from the rest of the world, both the religious and secular.
Exodus 31:13 to tell the people of Israel, “Keep the Sabbath, my day of rest, because it is a sign between you and me for all time to come, to show that I, the Lord, have made you my own people.
Identifying and defining a people that God can call His own is foundational to the New Covenant.
Hebrews 8:10 For this is the new covenant that I will make with the house of Israel after those days, says the Lord: I will put My laws in their mind and write them on their hearts; and I will be their God, and they shall be My people.
The devil can and does have his people with the last six commandments but he can't with the first four.
1 Peter 2:9-10 But you are a chosen generation, a royal priesthood, a holy nation, His own special people, that you may proclaim the praises of Him who called you out of darkness into His marvelous light; who once were not a people but are now the people of God, who had not obtained mercy but now have obtained mercy.
This can't happen without God's Law. Listen.
Exodus 19:6 "you will be for me a kingdom of priests and a holy nation.’ These are the words you are to speak to the Israelites.”
The very next words that God gave them was the Ten Commandments. If they/we obeyed them it will identify them/us as His people.
Exodus 12:49 "One law shall be for the native-born and for the stranger who dwells among you.”
Leviticus 24:22 "The same law applies whether he is an outsider or an Israelite. I am the Lord your God.’”
Whether Jew or Gentile we all love the Lord by obeying Him, that includes honoring the seventh day.
Isaiah 56:6-8 As for the Gentiles, the outsiders who join the people of the Lord and serve him and love his name, who are his servants and don’t desecrate the Sabbath, and have accepted his covenant and promises, I will bring them also to my holy mountain of Jerusalem and make them full of joy within my House of Prayer. I will accept their sacrifices and offerings, for my Temple shall be called “A House of Prayer for All People”! For the Lord God who brings back the outcasts of Israel says: I will bring others, too, besides my people Israel.
Let us join with the people of the LORD, through the shed blood of Jesus Christ, and serve Him and love His name.
Ephesians 2:11-13 Therefore remember that you, once Gentiles in the flesh—who are called Uncircumcision by what is called the Circumcision made in the flesh by hands— that at that time you were without Christ, being aliens from the commonwealth of Israel and strangers from the covenants of promise, having no hope and without God in the world. But now in Christ Jesus you who once were far off have been brought near by the blood of Christ.
Do away with the Ten Commandments and you do away with that which defines God's people. This is Satan's number one tactic.
Revelation 12:17 And the dragon was enraged with the woman, and he went to make war with the rest of her offspring, who keep the commandments of God and have the testimony of Jesus Christ.
1 Corinthians 7:19 Circumcision is nothing and uncircumcision is nothing, but keeping the commandments of God is what matters.