How can you be sure that Saturday is the 7th day if you are not sure that Sunday is the first day of the week?

Answer 1

You are obviously asking a scriptural question. The Torah designates days of the week based upon the Moon cycles. The new moon is the beginning of the lunar cycle. The new moon is a santified day of each month-set apart for it's Creator. Interestingly, there is to be no buying or selling on it. The new moon each month begins the night that it is spotted and includes the following day. So on your calender, it would be the day following that all darkened circle representing the new moon(if your calender designates such). It also encompasses the evening(only) of the day the all darkened circle it abides in. Each scriptural day actually begins at dusk/dark/night.

The first day following this day is day 1, then day 2, 3, 4, 5, 6, 7 of the week. Day 7 is neither Saturday nor Sunday necessarily, but it is the day of rest(consequently no buying or selling ought be done on it as well). After Day 7 we start over 1,2,3,4,5,6,7. This continues four times till the next New Moon-then repeated.

This was established so that the seventh day could never be lost...after all, the moon's orbit is established forever.