It takes a holy God to make holy time. He made no other time holy than His Sabbaths. Man can be made holy by God as well, but man cannot make something holy because he does not possess a holiness that can be passed on to anything. It takes a holy God to make something holy, thus any other day than what God has made holy—even though billions of men may proclaim it to be holy time—cannot be holy time. It is utterly impossible; Sunday cannot be made holy.
This means that the Sabbath is worthy of respect, deference, and even devotion that cannot be given to other periods of time. It is set apart for sacred use because it is derived directly from God. Because of God's assignment of the word "holy" to the Sabbath, this day is changed into something special. The general thrust of "holy" is different. The root word means "to cut," "to cut out," "to separate from," or "a cut above." The Sabbath is separate from other days, even though it is a part of the same cycle. It has been cut out, apart from, the other days—that is, sanctified. It is a cut above other days because God made it holy. It is different.
The Sabbath, then, is different from the common or ordinary. The other six days are common, and they are given for the pursuit of the common and ordinary things of life. On the Sabbath, we should strive to avoid those mundane things that promote making the Sabbath into an ordinary day. The Sabbath is a day for special things, different things.
The example of Moses and the burning bush illustrates what makes the day holy. It is not merely because of a proclamation by God. The burning bush provides a biblical example of how something becomes holy:
So when the LORD saw that he turned aside to look, God called to him from the midst of the bush and said, "Moses, Moses!" And he said, "Here I am." Then He said, "Do not draw near this place. Take your sandals off your feet, for the place where you stand is holy ground." (Exodus 3:4-5)
This is what makes the Sabbath holy. Because God was present, Moses had to treat the ground in a different way—with a respect and deference that one would not give to something common. Until God put Himself in that area, the ground where Moses saw the burning bush was no different from all the other ground in the area. But as soon as God put His presence there, it became sacred—holy.
It became holy by means of a spiritual action. Holiness is not something that is physically discerned. (It is interesting to note in this context (in Exodus 3:1-5) that Moses was not aware that the ground was holy until God told him!) So the Sabbath is a spiritual thing. Its holiness must be revealed to a person (I Corinthians 2).
How do things become holy? Like time and areas of ground, they become holy because God puts His presence in them. For the sake of His people and His spiritual creation, God's presence is in the Sabbath. We do not know how He does it. Somehow, He puts His presence into the weekly Sabbath and into His holy days, making them different to those to whom He has revealed that those days consist of holy time.