Mat 15:4 For God commanded, saying, Honour thy father and mother: and, He who curses his father or mother, let him die the death.

In the Sermon on the Mount after Christ teaches the Beatitudes, he goes through several of the ten commandments and raises the bar on morality. Not only shouldn't we kill, but we should turn the other cheek. One commandment he didn't mention at the time was this one. He fills in that gap now. Christ sees parents as a symbol for the union of the physical and mental in a relationship. That union creates a new spirit and new life. Words are symbolic of our mental powers. If we turn our mental powers against the union of mind, spirit, and body that creates a new spirit and life, the result is a separation of mind, spirit, and body in death.

"Honour" is from timaô , which means "to revere," "to honor," and "to value." It even has a sense of value in an economic sense meaning "to estimate," which has the same root as our word "to esteem."

"Curses" is from kakologeô, which means "to revile" and "to abuse." Literally, it means "bad words."

"Let him die" is from teleutaô , which means "to bring about," "to accomplish," "to finish," and "to die."

"Death" is from thanatos , which means "death," and specifically "a death sentence." In Greek, it has the clear meaning of separating the spirit from the body.