In Genesis Yahweh established the Sabbath day by resting on the seventh day of creation. That put in motion the Sabbath that fell every seventh day perpetually up to today, and created the seven-day week throughout history. He called it THE Sabbath, not A Sabbath. The numbering of weekdays in today’s Gregorian (Catholic) calendar does not correspond to the scriptural calendar. Those who accept the lunar Sabbath doctrine are attempting to start not only the month but also the week by the new moon. See http://www.yrm.org/lunarsabbath.htm for a detailed study of this doctrine.
Nowhere in Yahweh’s Word are we instructed to start the week by the moon. Month, yes, but not the week. Yahweh has already done that for us by creating the Sabbath on the seventh day, to which the Jews for thousands of years and Yahshua Himself adhered.
If you are thinking that establishing the Sabbath by the new moon is somehow more scriptural than our wall calendars, consider again that it was Yahweh who made the perpetual Sabbath, which has always been in rotation in the week since the seventh day of creation. You can’t get more accurate than following Yahweh’s own example and practice. Yahshua had no issue with the day the Scribes and Pharisees kept for the Sabbath and never mentioned a problem with the Sabbath calendar. The Jews have since kept the same day Yahshua kept.
By replacing His divinely or-dained week with their own system, lunar proponents are in violation of Deuteronomy 4:2; 12:32 and Revelation 22:18. The first fatality in this man-made scheme is the erroneous counting of Feast days like Pentecost with partial weeks instead of full weeks (Lev. 23:15), and the automatic creation of leftover days and partial weeks at the end of the month that no one knows what to do with.
As for the seasons’ slipping further and further back in the year, that won’t happen if we use the scriptural Abib barley to begin the year. The seasons take care of themselves when we follow Yahweh’s calendar.
For more in-depth research see:
ABCs of the Biblical Calendar
Sabbath Keeping- Answering the Arguments