Mathematics obsesses over eternal and immutable truth, and, except for the choice of different axioms, does not accept "a multitude of paths to truth and libera

Mathematics obsesses over eternal and immutable truth, and, except for the choice of different axioms, does not accept "a multitude of paths to truth and liberation". Also, any sense of "original purpose" of religion you may have for either religion you mention is a construct from your perspective; neither Judaism nor Christianity indicates an "original purpose" for themselves at any point. Similarly, they do not indicate an "original purpose" for Shabbat; there is only a few repeated words surrounding the commandment to observe it. To say there is nothing special about Saturday implies that you have already entirely missed the point; it is only because of this tradition (or possibly the Babylonians, who may have had it first) that we use a seven day week at all. Actually, the tradition regarding what qualifies as work is significantly more specific than you seem to think; the 39 melochot are the categories of tasks involved in the construction and operation of the tabernacle--all work on which was specifically prohibited for Shabbat, so associated tasks are prohibited into modern times. All systems of thought tend to calcify over time, as the same concepts and results continue to be repeatedly verified; one can't single out religion in this regard, just because the major religions are among the eldest organized systems of thought.