Sabbath keeping with all it's rules and regulations, was part of a covenant with Israel that is not binding on the body of Christ/Christians under the new covenant.
*Colossians 2:16 - Therefore no one is to act as your judge in regard to food or drink or in respect to a festival or a new moon or a Sabbath day 17 things which are a mere shadow of what is to come; but the substance belongs to Christ.
Even when sabbatarians set out to worship on the sabbath, are they truly "keeping the sabbath?" To "keep the sabbath" as it was required in the Old Testament under the old covenant of law would involve compliance with specific regulations (Exodus 16:23; 35:3; Leviticus 23:32; Jeremiah 17:21) that were strictly enforced.
If sabbath day observances are still required, so would the burnt offerings which went along with them (Leviticus 19:30; 23:2-3; Numbers 28:1-10; 29:39-40; I Chronicles. 23:30-31; II Chronicles 31:2-4; Isaiah 1:13). So no kindling a fire in any of your dwellings on the sabbath. (Exodus 35:3) Every man must remain in his place on the sabbath. (Exodus 16:29) No trading. (Amos 8:5). No marketing. (Nehemiah 10:31; 13:15,19)
These were commanded by God to Israel. (Exodus 35:1)
The Word of God makes it quite clear that sabbath observance was a sign between God and Israel: "The Israelites are to observe the Sabbath, celebrating it for the generations to come as a lasting covenant. It will be a sign between me and the Israelites forever, for in six days the Lord made the heavens and the earth, and on the seventh day he abstained from work and rested." (Exodus 31:16-17)
In Deuteronomy 5, Moses restates the Ten Commandments to the next generation of Israelites. Here, after commanding sabbath observance in verses 12–14, Moses gives the reason the sabbath was given to the nation Israel: "Remember that you were slaves in Egypt and that the Lord your God brought you out of there with a mighty hand and an outstretched arm. Therefore the Lord your God has commanded you to observe the Sabbath day." (Deuteronomy 5:15)
If the seventh day sabbath is still in affect, then why don't sabbatarians seek to obey ALL that the LORD commanded? How can a person keep a certain law when he keeps only part of it?
If the Sabbath day laws were still in effect today, then according to Exodus 31:12-18; 35:1-3; and Numbers 15:32-36, anyone who profaned the sabbath was put to death and any person who does any work on it, that person shall be cut off from his people.
Now who is going to enforce that? The Jewish synagogue? The Seventh day Adventist church or perhaps the Government? Since we do not live under a theocratic state as ancient Israel did under the old covenant of law, no sabbatarian can live consistently under these Mosaic regulations.