>>What changed was not the weaponry so much as the modern mind, jammed with ultra-violent images from movies, TV and especially first-person-shooter video games from childhood on.
The thing that changed in the modern mind was the end of cultural Christianity and its replacement with Humanism. The FPS video games and movies followed from that.
In Humanist ideology, each human is the pinnacle of morality and that is situational. So when some nutjob decides to end his life, the morality of taking 30 innocent people with him is easy: “It’s what I want. I have the means. I will do it because there is no higher authority than me that can touch me after I’m dead.”
Every mass shooter has this basic philosophy, whether they call it Humanism, Existentialism, Nihilism—even Islam is really Humanism with a thin veneer of religion applied to cover the political goals of the ideology.
I’ve argued with atheists about morality. Their take is that morality comes basically from a group consensus. When I point out that group consensus changes and that eventually it could change to say that rape is okay against certain people. They immediately deny it and then I point out that many Muslims believe that it is okay to rape and kill non-Muslims and they are rapidly taking over Europe.
I also point out that the belief in no higher power in the afterlife or no afterlife at all leads many to go against conventional morality and decide that they can do anything they think they can get away with. After all, if Christians are forbidden to impose God’s morality on them, who are they to impose their morality on someone else?