Why were changes made in Torah laws necessary
why should Jews obey these changes since they differ from the divine Torah law?
Maimonides wrote in his Guide of the Perplexed 3:32 that the Torah had to write laws that the Israelites could accept, laws that were not ideal. The Israelites accepted “the customs that existed in those days generally among all men, and the mode of worship in which the Israelites were brought up.” The Torah recognized, Maimonides wrote, that it was impossible to wean the people suddenly from ancient heathen notions. “It was in accordance with the wisdom and plan of God … that God did not command us to give up and discontinue all these kinds of service, for to obey such a commandment would have been contrary to human nature, for people generally cleave to that to which they are accustomed.”
Thus, for example, Maimonides cites sacrifices, which he says God does not need or want. The laws of slavery are another example. We will see many more later in this book. In Guide 3:51, he states that people will ultimately improve and come to understand true worship and the proper way to deal with other humans.
The need for change is contained in the Torah, for while allowing the continuance of non-ideal practices, the Torah modified the non-ideal practices somewhat and showed that they should be modified further. It allowed sacrifices, for example, but restricted them greatly to certain places and times, and disallowed certain animals used by pagans. It allowed slavery to continue but established many laws that required masters to treat slaves humanly, to the extent that the rabbis said: he who acquires a slave acquires a master over himself.
Jews recognized the Torah’s intention and did away with sacrifices, which could have continued even after the temple was destroyed in 70 CE, and abolished slavery. But despite the radical changes, the new laws were in the spirit of the intensions of the Torah laws. Thus while it is true that Jews are no longer literally Torah Jews but Rabbinic Jews because of the changes, in a large sense they are true to what the Torah desires.
Once Maimonides’ teaching in 3:32 is recognized that the Torah laws are in many ways not ideal, the Torah wanted them to be changed, the changes were made in the spirit of the Torah, and Jews are true to the Torah, the question “why observe Rabbinic Judaism since it is not Torah Judaism, nor is it divine law?” is answered. In a word, this is what the Torah wants, what it is teaching, the goal it wants Jews to attain.