Jesus said:
[17] Think not that I have come to abolish the law and the prophets; I have come not to abolish them but to fulfill them. [18] For truly, I say to you, till heaven and earth pass away, not an iota, not a dot, will pass from the law until all is accomplished. [19] Whoever then relaxes one of the least of these commandments and teaches men so, shall be called least in the kingdom of heaven; but he who does them and teaches them shall be called great in the kingdom of heaven.
Matt. 5:17-19
(Revised Standard Version)
Over the centuries, certain men thought to exalt themselves above God by changing His commandments, specifically the Fourth Commandment:
[8] Remember the sabbath day, to keep it holy. [9] Six days you shall labor, and do all your work; [10] but the seventh day is a sabbath to the LORD your God; in it you shall not do any work, you, or your son, or your daughter, your manservant, or your maidservant, or your cattle, or the sojourner who is within your gates; [11] for in six days the LORD made heaven and earth, the sea, and all that is in them, and rested the seventh day; therefore the LORD blessed the sabbath day and hallowed it. (Exodus 20:8-11, RSV)
For three centuries after the death of Jesus, his faithful followers kept the Fourth Commandment Sabbath of sundown Friday through sundown Saturday. However, during the reign of Roman Emperor Constantine, in AD 321, Constantine decreed, “All judges and city people and the craftsmen shall rest upon the venerable day of the sun…”
http://en.m.wikipedia.org/wiki/Sabbath_in_seventh-day_churches?wasRedirected=true
The change was not made on Biblical grounds, rather it was a political change designed to increase the size and therefore power of the church by including pagan Sun worshipers.
To this day, no one can provide scriptural proof that the Sabbath should be changed to the first day of the week (i.e., Sunday). Thus, in order to keep His Commandments, a Christian must keep the Lord’s Sabbath day holy. To do otherwise is to break God’s commandment.
