Quote:"Remember the Sabbath day, to keep it holy." -- Exodus 20:8
"One man esteemeth one day above another: another esteemeth every day alike. Let every man be fully persuaded in his own mind." -- Romans 14:5
Lets briefly consider the Christian sabbath. To the Jews it had been not only a religious regulation but also a law of the land. It is interesting to note here that the sabbath wasn't observed by the priests. The Jews have an expression; "There is no sabbath in the sanctuary." - (The Temple, by A. Edersheim, 1874, p. 152.) (Matthew 12:5) and infants were circumcized on the sabbath if the sabbath happened to fall eight days after he was born. (Leviticus 12:2, 3 / John 7:22)
Jesus grew up under the law, but he also noted that it was lawful to do fine things on the sabbath (Matthew 12:12) this caused some problems for some religious leaders because they had a religious idea of what the purpose of the law was while missing the heart of the law. They were over zealous.
Christ was the end of the law (Romans 10:4) but some people didn't (don't) recognize Christ as such.
It is important to note here that though Christians were not under the law of Moses in a religious or legal (of the land) sense yet they could still observe the sabbath.
Colosians 2:16-17 - Therefore let no man judge you in eating and drinking or in respect of a festival or of an observance of the new moon or of a sabbath, (Footnote: or 'sabbaths.') for those things are a shadow of the things to come, but the reality belongs to the Christ.
What happened is that there was a change, rather than a contradiction. The Jews rejected Christ - the Messiah, the son of God. The King of a kingdom that was no longer represented by Israel and its Kings.
A brief aside regarding the 'Christian Sabbath.'
Not until 321 C.E. did Constantine decree the first day of the week (rather than the 7th), Sunday from the Latin dies Solis, a title associated with astrology and sun worship as the 'sabbath' for everyone but farmers. Clark’s Biblical Law says: "Constantine the Great passed an edict commanding all judges and inhabitants of cities to rest on the venerable day of the Sun."