Actually, if you study many religions, it appears that there may have been seven big religions, and their holy day was on different days of the week.

And if you take the meanings of the weekdays, Sun-day Moon-day, Water-day, Tree-day, Fire-day, (sorry, don't remember all the names and meanings) That "christians" started off as worshippers of Saturn (saturday) and then all got converted to sun worshipers (sunday).

The web-interconnections is really intense, so it seems there is something there... but, we don't know because the vatican won't share its books with the rest of the world.