In the Bible, the first six days of the week are not named. The first day of the week is simply designated yom echad—“day one.” The second day is yom shini—the “second day,” etc. However, in the western world, the days of the week are named—each one in honor of a different god.
Sunday, the first day of the week is named in honor of Sol, the Roman sun-god.
Monday, for Artemis, the Greek moon goddess.
Tuesday, for Mars, the Roman god of war.
Wednesday, for Mercury, the Roman messenger of the gods.
Thursday, for Thor, the Scandinavian god of thunder.
Friday, for Venus, the Roman goddess of love.
And Saturday, for Saturn, the Roman god of agriculture.
In the Bible however, the seventh day is named—it is called the Sabbath (Heb. Shabbat), from a word that means “to cease, desist, or rest.” It is called the Sabbath because on it God “rested from all the work of creating that he had done” (Gen 2:2-3).
The seventh day of the week, the Sabbath (Exo 16:26; 20:10) and the first day of the week, yom rishon (Sunday) are not the same day.