The opponent of God has a Counterfeit for many things of God--including a Counterfeit Sabbath by getting men to transfer the Solemnity of the 7th Day Sabbath (which identifies God as Creator - therefore solidifies His claim as God) to the first day of the week. By doing so the opponent of God sets himself up as a Counterfeit "god" of this world....Remember the sabbath day, to keep it holy. Six days shalt thou labor, and do all thy work: But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, .....For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
Exodus 20:8-11