In Leviticus, God sets all these rules for his chosen people to follow. Why then do we as Christians not follow these rules? Weren’t we all Jews to begin with? Wasn’t Jesus Jewish? Wasn’t he a descendant of God’s chosen people? So, shouldn’t we be following his traditions that were set down for him?
The answer to this question is complex. First of all, yes, Jesus was Jewish. It is also true, however, that he took a radical approach to his Jewish faith. He believed he had come to fulfill various parts of the law and to inaugurate a new covenant.

The obligations of the new covenant would have some overlap with the old (for example, “honor thy father and mother” is affirmed in the Old Testament law and also by Jesus), but it would also have various differences. Instead of “a life for a life,” Jesus called upon his followers to love their enemies and turn the other cheek. Thus, the simple answer to the question is that Christians are obligated to obey the commandments of the new covenant, not the old covenant, and sometimes this corresponds with what the Old Testament law says, and sometimes it does not.
—Ben Witherington III