Professing Christians - Many will be saying that Jesus is the Christ and deceive many?

Think about it. The other commandments are moral laws that impact every person. This particular command was given to the jewish nation before the church age. All of these "laws" of God remain applicable to our behavior, but the "NEW" Testament is a new covenant with the entire church, and the day of the week in which we gather together and worship as a day of rest began with the inspiration of the Holy Spirit. Otherwise, I am certain that we would see specific preaching and teaching in the NT regarding saturday vs. the first day of the week. The only things we see in scripture is the Spirit (through man, ie, Paul) telling us that it is okay to gather on this "first day of the week, as the manner of some is." That fact alone is enough evidence for me to not concern myself with what day, but rather, in what manner do I display the life of Christ in my dealings with the world.