Let's begin the cultural shift with the introduction of a new phrase: morally retarded.
The phrase is an accurate description of those who go on these mass killing sprees. Too many messages in the popular culture associate a willingness to commit violence with a superiority of character, where the person is depicted as having transcended normal limits.
The opposite is true. People who can commit violence are morally retarded and need to be depicted that way. They've never developed limits because of their moral retardation. Their decision-making capacities are skewed. The result is violence our entire society has to suffer.
Let's change the conversation about violence.