Those who hold to the calendar-day view of creation frequently use the establishment of the Sabbath day as a defense that the creation periods must have been 24-hour days. God instituted the Sabbath day with the fourth of the Ten Commandments, given in Exodus 20:8–11. “Remember the Sabbath day by keeping it holy. Six days you shall labor and do all your work, but the seventh day is a sabbath to the Lord your God. On it you shall not do any work …. For in six days the Lord made the heavens and the earth, the sea, and all that is in them, but he rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy.”
In order to use this passage to interpret the Genesis creation account, we must first try to understand the purpose of the Sabbath day. Is it merely that we must rest on the Sabbath because God rested on the seventh day? God created fish on the fifth day. Does this mean that we should spend one day each week creating fish? There must be more to it than this. Now it is true that at the end of God’s work of creation, he specifically declared the seventh day to be holy. However, this in itself does not establish that God’s holy day of rest is the same in every way as the day of rest that God commanded Israel to observe. More study and analysis are necessary in order to make this connection. There are many perspectives among Christians concerning the purpose of the fourth commandment, and a detailed study of these is beyond the scope of this blog. For my purpose, however, I will divide them into a few broad categories.
One view is that the Sabbath day was established in order to benefit its observers in some tangible way, such as by giving them rest from their work. Assuming this view, must the nature and duration of man’s rest be the same as the nature and duration of God’s rest? I do not thing that is a necessary condition. God’s rest may well serve as an example for man’s rest without being of the same duration, and six periods of work followed by one period of rest can serve equally well as a pattern for both the Sabbath day and the Sabbath year.
Another view is that the Sabbath was established as a memorial of creation. A memorial, however, does not need to be the same in every way as the thing remembered. The Lord’s Supper is, at least in part, a memorial of Christ’s death (Luke 22:19). This does not mean that every time we participate in the Lord’s Supper, we literally die in the same manner as Christ did. (Although there are differing views within Christianity concerning the Lord’s Supper, I think all will agree with this.) In the same way, a Sabbath lasting 24 hours each week as a memorial does not necessarily indicate that God’s rest lasted 24 hours at the end of a single week.
Others argue that the Sabbath was instituted as a sign and seal of the Mosaic Covenant. However, this interpretation bears no direct connection to creation at all. With this understanding of the Sabbath day, the reference to creation in Exodus 20 is not useful in showing that God’s rest must have been of the same duration as the Sabbath rest that God commanded the Israelites to observe.
In short, the fact that Exodus 20 relates God’s day of rest to the Sabbath day does not necessarily mean that these two things must be the same in every way or even that they must be of the same duration. In order to prove on the basis of Exodus 20 that the days of creation were ordinary 24-hour days, first it must be shown clearly from scripture that there is a specific purpose for the Sabbath day that relates directly to creation and that is more substantial than “do this because God did it.” Next, it must be shown that the connection between the Sabbath day and the seventh day of the creation week cannot serve its purpose unless these days are of equal duration. I have never heard this argument specifically made, and I am doubtful that a strong case can be made for it.