The early church, we know from the New Testament, had the habit of meeting on the first day of the week (our Sunday) which was called "The Lord's Day".   It was presumed that since Christ rose from the dead on the first day of the week, then that day ought to be the accepted day of congregational gatherings.  Many today mistakenly think that the directives for keeping the Sabbath holy now are applicable to Sunday.  There is nothing in Scripture that would even hint that the Sabbath is now Sunday instead of Saturday.

So, are we to keep Saturday, or Sunday?  The answer is…neither…and both.

The whole matter is clearly answered in the book of Hebrews chapter four.  In order to understand it, we need to discover the exact context of a word used in that chapter.  In the preceding chapter, the author states that we are to            

            exhort one another daily, as long as it is called "Today" , lest any
            of you become hardened through the deceitfulness of sin. ( 3:13)

We are told that we are to encourage each other, as long as it is called “Today”.  When is the day “Today”?   Every day.  Having a day named "Today" is an idiom which is clearly is meant as an expression for "daily".  Every day that we experience is "Today."  In context, we are to exhort and encourage our brethren every day, since every day is "Today".  Now the exact same term is applied to the Sabbath in chapter four.  The verses 4 through 7 read:

            For He has spoken in a certain place of the seventh day in this way,
           "and God rested on the seventh day from all His works."  and again
             in this place "They shall not enter my rest." Since it remains that some
             must enter it, and to those it was first preached did not enter because of
             disobedience, again He designates a certain day, saying in David,
            "Today", after such a long time, as it has been said, "Today, if you
             hear His voice, harden not your hearts."

God has replaced the seventh day Sabbath with a new Sabbath which is celebrated “Today”.  We are no longer bound to a single sanctified day of the week.  In the years before, because of the hardness of men's hearts, one day had to be set aside each week when we could rest and meditate on the Lord and His word.  But now God designates another day.  It isn't Sunday.  It isn’t Saturday.  It isn't Christmas or Easter.  It is "Today".  The Sabbath was a type or a foreshadowing of the rest we have perpetually before God in Christ.  No longer do we have to "work" for our salvation, since it was procured by Christ on Calvary.  Paul wrote to the church at Colossi in Colossians 2:16,17 that we should let

            no man judge you in food or drink, or regarding a festival or new
            moon or Sabbath, which are a shadow of things to come, but the
           substance is of Christ.

        This new understanding is also carried out in other New Testament writings.  It would seem that the early church did not put the same importance on the recognition of special days that many Christians do today.  Paul wrote to the Romans that

            one esteems one day above another, another esteems every day alike.
            Let each be fully convinced in his own mind.  He who observes the
            day, observes it to the Lord;  he who does not observe it, to the Lord
            does not observe it.                 (Romans 14:5,6)

       The real issue is not which festival one keeps, but whether the Lord is sanctified in their hearts all the time.  Observing the Sabbath then, means having the God first in your life every day…as long at it is called “Today.”