The 7th day sabbath is not the Law but is one of the laws or commandments of God. It is the sign which distinguishes belonging to Jesus God versus Sunday which contrarily distinguishes belonging to Satan or to Babylon (Mark 7:7, James 2:10).
OUR SALVATION HANGS ON ONE DISOBEDIENCE OR ONE DISAGREEMENT
Once we got the sabbath correct, we remain vulnerable to fall to Satan if we are not revealed who Jesus is in Heaven (Luke 10:22) so that we can believe it (John 8:24) and confess it with our own mouth (Romans 10:9-11).
The quest for salvation also depends on the branding of the seventh day sabbath because it is inconceivable that Jesus has been forced to accept the first day (Matthew 12:8; Mark 2:28) when He called light into existence in our our universe, just because men decreed so (Daniel 7:25).
7th day Saturday Sabbath has been part of the curriculum of holiness or sanctification (Leviticus 19:2, 20:7-8, Hebrews 12:14) since the wilderness and, as such, cannot be repealed by any man (Numbers 15:40).
Ezekiel 33:13 ASV
(13) When I say to the righteous, that he shall surely live; if he trust to his righteousness, and commit iniquity, none of his righteous deeds shall be remembered; but in his iniquity that he hath committed, therein shall he die.