In the times before Christ, a person would do something to offend another, and a fight would commence between them and their families. Often times these fights would continue for generations. Thus the Old Testament rule was to only do what was equal, rather than escalating the conflict.
However, Jesus tell the people to take it one step further. Instead of taking an eye for an eye, Jesus tells the people to turn the other cheek. Instead of responding with anger or trying to get revenge, conflicts will dissipate if love is shown. This is a good concept for us, that we should be focused on what God wants for us rather than what we want for ourselves.
The "golden rule" tells us to treat others how we would like to be treated. But how often do we pray for those you we don't get along with? Jesus tell us to do just that in Matthew 5:44. He call Christians to live a life better than Pharisees and tax collectors. "If you greet your brothers only, what do you do more than other? Do not even the Gentiles do the same? (Matthew 5:47).
Chapter five of Matthew ends with perhaps the hardest commandment in the Bible: "Therefore, you are to be perfect as your heavenly Father is perfect." Not only does this command encompass all others, it hold us to a divine standard rather than a human one. But can we really be perfect? God would surely know that humans are fallible and that we can't do right even if that is what we want.
However, this argument could be carried to all the other laws: if we are going to eventually break them, what is the point of following them at all? Jesus destroys this argument by firmly telling people to be perfect. The word perfect means finished, done with, complete. If we constantly try to be like Jesus, our human nature will be changed by God.
