The Sabbath is not based on the moon. There is no such thing as a lunar Sabbath on God's calendar. There are many ways to disprove this false teaching and someday I will write an article on this topic. The Sabbath is literally impossible to keep from a lunar counting method as there are not exactly 28 days in a lunar month, forcing some weeks to be more than 7 days, breaking the seven day mandated Sabbath cycle. The Sabbath started at creation and was simply observed every 7 days from then till now.
The Jews in the first century observed the Sabbath on the Roman Saturday, as writings from that period testify to. With that being said, if the Sabbath was being observed on the wrong day, and the Sabbath was the fourth commandment on the top ten, I can assure you that Yeshua would have mentioned something, especially during the time where He was accused of breaking the Sabbath. That would have been the time to tell them that they were celebrating the Sabbath on the wrong day, but He didn't. Furthermore, He not only went to the synagogue and celebrated the Sabbath every single Saturday, but all of the disciples and their disciples did the same for hundreds of years without fail. If the lunar Sabbath was the valid Sabbath, then they would have been celebrating the lunar Sabbath. But they weren't. The entire reason why Rome stamped approval on changing the Sabbath day to Sunday was BECAUSE the Jewish Christians were celebrating the Sabbath on Saturday. Although there is much more that could be said on this subject, this evidence alone invalidates the idea of the lunar Sabbath.