The word raca is used only once in the New Testament – Matthew 5:22. The word is of Aramaic origin. Aramaic is a Semitic language as is Hebrew. The two languages are very similar. Raca is likened to the Hebrew word rak (H7386). The word means “empty, worthless, vain, shallow brains”. It was a word of contempt.
Some commentators say that in that culture it meant that a person was worthy to be “spit upon” when they were referred to as raca. Of this I am not certain, but it was definitely a word which devaluated a human life.
In the passages Matthew 5:21-26, Yeshua is speaking about murder. The sixth commandment teaches us that we should not murder. Here, Yeshua expounds upon the “fuller” meaning of the Torah commandment. To begin, He tells his listeners that murder begins in the heart as a seed. That seed can grow into murder if not quenched in the beginning. All sin begins as a seed. (See James 1:14-15)
He gives three examples to teach His lesson. First, He deals with anger. A person who commits this offense is in danger of being judged before a tribunal or civil justice system. This could have been a court of peers, or the Beit Din. A Beit Din was a Jewish Civil Court. In Hebrew it means “House of Judgment” . Yeshua was tried before the Beit Din.
Second, He deals with contempt by calling someone raca (worthless, empty). The person guilty of this offense was in danger of being tried before the Jewish Great Sanhedrin.
Third, He deals with someone who is guilty of calling a person a fool. The term fool showed that the offender had an intense hatred for another human being and considered them a mortal enemy. This offender stood in danger of being thrown into Gehenna. (See my teaching on Hell) Gehenna or the Valley of Gehenna was an actual place in Jerusalem which was associated with judgment and complete destruction.
Here we see a seed that began in the heart could have the potential of growing until it became a sin, bringing forth fruit, which was punishable by death. Death is exactly what the Torah says should happen to a person who commits murder. In each example the guilt of the person became greater and the consequence of their action became more severe.
Notice that the offender did not have to actually physically "murder" the other person. He had already murdered them in his heart; by his hatred. Hence, Y'shua makes His point; murder begins in the heart.
We should guard our hearts carefully, for from the heart the mouth speaks. (Luke 6:45)