This chapter, as all chapters in Yeshayahu from 40 and on, contains a message of consolation. Specifically, this chapter tells us that G-d cannot be contained in the physical Mikdash, nor is He interested in sacrifices that are not offered with sincerity. The month is defined by a natural phenomenon - the cycle of phases of the Moon, and is available to all people to experience and be inspired by. The Shabbat represents the basic belief that G-d created the world. It is not connected to a natural occurrence.
Some people come to belief from experiencing something in nature.
Others just believe. Either way, in the case of Shabbat and Chodesh, we are dealing with concepts that can have a popular appear. All Rights Reserved.