Matthew 5: 21-32  Jesus said that He came to "fulfill"  the Law, not abolish it.  The Law was given to reveal God's standards for His people, that they might be "perfect" as their "heavenly Father is perfect." Perfect here is the Greek word "teleios" meaning complete.  It is God's prescription for holiness.  Jesus never annulled the requirements of the Law.. He opened up the true meaning, the underlying purpose for it.  We will look closer at the first two of these... 

v21-26  The Law says, "You shall not commit murder."  Jesus explained that this commandment goes beyond the idea of the act of murder.. it addresses the attitude of the heart towards others.  Anger, ridicule, oppression, derision, unforgiveness, even debt... all these things ( and more) that separate and divide brothers against brothers.. these are the same as murder in the eyes of God.  If we want to be "perfect" - pure and holy and complete - being salt and light - then we need to confess and repent of that sin in our hearts, not just avoid the act of murder.  Jesus said over and over again.. "Love one another".  That is the standard that God holds us to.. a much higher standard than the way the Law was being used by Israel. 

v27-32 The Law says, "You will not commit adultery".  Again, Jesus addresses the attitude of the heart- lust is a sin in the heart - so much so that Jesus says it would be better to get rid of your eyes or cut off your hand so that you won't sin and be sent to hell.  Divorce was also a sin problem, Jesus taught, because the attitude of the heart was hateful towards the wife that was sent away.  She would have no recourse, no future, and no hope.. This is not according to God's desire for His people.. for He designed marriage to be a oneness that would not be broken.  The exception here "for the cause of unchasity" makes sense in this context, because the oneness had already been broken. 

Father in heaven, Your love for us is evident in Your Law, for You want was is best for us.. so that we can be complete... "perfect" as You are perfect.  We again come before You and confess that we are poor in spirit.. hungering for Your righteousness, trusting in the cleansing blood poured out for us by Christ Jesus, so that we might be whole.  Oh how we thank You for the cross.. for the One who became the propitiation for our sins.  Come and sanctify us through and through, Spirit of God, that we might shine with the Light of Jesus in a world filled with darkness. Be exalted O God! Amen.