Question of the week: Why are there seven days in the week and not five, six, eight, or ten? How do we know that Sunday in our calendar is the Sunday Adam or Abraham celebrated?
My answer: During the French Revolution the revolutionaries—in their attempt to de-Christianize society and increase productivity—experimented with a ten-day workweek from 1793–1805. Similarly, during the Soviet era in Russia, the communists experimented with a five- and six-day workweek from 1929–1940. In both cases, there was a notable drop in work productivity and both the French and the Russians reverted back to a seven-day workweek. These experiments demonstrate that we humans are biologically and spiritually designed for a week of six workdays followed by a seventh day where we cease from our work and focus on the most important issues of life. I wrote about and cited these experiments in my book, Navigating Genesis, chapter 9, pages 85–86.
As for our calendars, it is not possible to prove or disprove that our Monday corresponds to Adam’s Monday or to Job’s Monday. It is not necessary. As Paul explains in Romans 14, what is important is that we humans take one day out of our seven-day week to cease from our work and focus on the most important issues every human being faces, namely the spiritual issues of life.