Jesus recognizes that it is not enough to merely not "do the deed." Anger toward a brother or sister pushes them away emotionally and disrupts relationships. Anger fuels a desire to "get even," to harm the other person. If not physically, then through verbal ridicule. We don't physically harm the other person, but assassinate their character. Jesus says this is liable to the judgment of hell. It is the same as murder as it destroys the other person's character. Worship is not acceptable as long as we harbor anger toward another in our hearts.
Likewise, lust is as damaging as adultery. It is not just the act that destroys marriages. It is the lust in the heart the directs our emotional connection to someone other than our spouse. However, in Jesus' day, lust was a physical attraction. Today, the internet creates lust through images, video, and on-line chat rooms. Whether married or not, internet pornography poisons the heart, destroying the ability to relate to people as people. They become objects, the image implanted in the brain for our own gratification.
The third community destroyer is dishonesty. Lying destroys trust. Jesus calls us to speak clearly and honestly with each other. We don't need excessive oaths to emphasize the truthfulness of speech. Our yes should by yes and our no should be no.
Jesus says if we want to have a community of love we need to check our motives not just our actions. The law was given to Moses to shape our minds and hearts, not just to control behavior. Loving, nurturing communities are built on the motives of the heart and not just outward actions. As we shower our loved ones with cards and gifts on Valentine's Day, let's be mindful that the best gift we can give each other is a heart free from anger, lust, and dishonesty.