I have a hypothetical question for you. †If God himself were to tell you (audibly speaking here) that your view of the Sabbath is incorrect, that it is in fact still valid (the biblical Sabbath of Friday sunset to Saturday sunset), would you take lightly to His decree, or would you humble yourself to Him? Again, just a hypothetical question. †Yes, I am a Sabbath observer. †In all fairness I asked myself the same question albeit the other way around. †I would certainly humble myself. †Have you ever even asked yourself that question? †If not, why?†
Since God said through Paul to the Gentiles, "And you, being dead in your trespasses and the uncircumcision of your flesh, He has made alive together with Him, having forgiven you all trespasses, having wiped out the handwriting of requirements that was against us, which was contrary to us. And He has taken it out of the way, having nailed it to the cross. Having disarmed principalities and powers, He made a public spectacle of them, triumphing over them in it. So let no one judge you in food or in drink, or regarding a festival or a new moon or sabbaths, which are a shadow of things to come, but the substance is of Christ" (Colossians 2:13-17), and since God cannot lie (Titus 1:2), nor does He produce confusion (I Corinthians 14:33); the question presupposed what cannot exist. It is a false question and requires no answer.
The questioner offers no proof, but ineffectively tries to make the questioner appear to be better than the answerer. Ironically, according to God's teaching, the questioner is disobeying God by denying that Christ's covenant has replaced Moses' covenant; yet the questioner wants it to appear that he is willing to obey. "Then He said, "Behold, I have come to do Your will, O God." He takes away the first that He may establish the second" (Hebrews 10:9).
See Answering the Sabbath Observance for more details.