Q. How should we understand this statement of Jesus: “Whoever therefore breaks one of the least of these commandments, and teaches men so, shall be called least in the kingdom of heaven; but whoever does and teaches them, he shall be called great in the kingdom of heaven”? How would you respond to someone who claimed that this statement meant that Christians were required keep the Mosaic Law (including circumcision, the Sabbath, dietary laws, etc.)?
I would respond, respectfully I hope, to someone who made that claim by saying that I believed they were taking the statement out of context and thus interpreting it to mean something other than it actually meant.
Jesus came teaching an inward righteousness that was based on becoming inwardly disposed to doing what God wants. Some people misunderstood him to be saying that it therefore didn’t matter what they did on the outside. So Jesus clarified his teaching. In the same passage where the statement you quote is found, he also said, “Do not think that I have come to abolish the Law or the Prophets. I have not come to abolish them but to fulfill them.“
What he meant was that if a person really were motivated by an inward desire to please God, then they would actually exceed the standards specified in the law. He goes on to give examples. Such a person would not only refrain from murder, they would not hate. They would not only refrain from adultery, they would not lust. And so forth. So the main point Jesus is making in the statement you quote is that the commandments in the law pointed how people could live with one another in the way that God intended, and that he had come not to set aside those commandments and the course they set, but to help people live in that way even more authentically.
We should also observe that Jesus was speaking to his fellow Jews when he made that statement. The Jews were required to observe certain insignia (such as the ones you list, the Sabbath, the dietary laws, etc.) to show that they belonged to the people of God. When the people of God expanded, through the work of Jesus, to include non-Jews, the question arose as to whether they had to keep the law. Large parts of the New Testament are devoted to this question, and the answer is a very clear “no.” So once again, anyone who claims that this one statement by Jesus means that all Christians must obey the specific requirements of the Jewish law is taking the statement out of context and failing to appreciate its meaning within the overall message of the New Testament.
I discuss this question in greater detail in a three-part series of posts that deals specifically with the case of Sabbath observance. That series begins here:
Are Christians required to keep the Sabbath? (Part 1)
Good Question 