" I tell you the truth, nothing will disappear from the law until heaven and earth are gone. Not even the smallest letter or the smallest part of a letter will be lost until everything has happened. Whoever refuses to obey any command and teaches other people not to obey that command will be the least important in the kingdom of heaven. But whoever obeys the commands and teaches other people to obey them will be great in the kingdom of heaven. I tell you that if you are no more obedient than the teachers of the law and the Pharisees, you will never enter the kingdom of heaven.
" You have heard that it was said to our people long ago, 'You must not murder anyone. Anyone who murders another will be judged.' But I tell you, if you are angry with a brother or sister, you will be judged. If you say bad things to a brother or sister, you will be judged by the council. And if you call someone a fool, you will be in danger of the fire of hell."
-- Matthew 5:18-22 (NCV)
This passage is clear enough, but it is taken very literally sometimes, when the spirit is far more symbolic than specific to murder or just the ten commandments.
As Jesus describes above, the SIN (the barrier that comes between you and God) in murder is not the physical act, but in the kernel of hatred that enters into you. That barrier between you and God is not specific to 'hard crimes'. This barrier forms the kernel of thought that comes before any sin. You separate yourself from God not by touching someone in adultery, but just by thinking too fondly of someone.
How To Be the Light: We teach the law through our actions and thoughts. By exercising restraint of our own thought, we not only keep the barriers of separation from forming between us and God, but we can break down the barriers that exist between us and others.