As cases such as this-beliefs that result victims and other people paying for the consequences, these nonsense beliefs have lost that right.
No. It is not these beliefs that lead to these actions. There are plenty who hold superstitious and scientifically unfounded beliefs that do not act in such murderous ways. Mental illness is not the same thing as prerational belief systems. Insanity and murder are not the result of a prescientific belief systems. To claim otherwise, is unsupportable. People who are rationalists, can also suffer from mental illnesses and do horrible things like this too. The commonality is mental illness, not belief systems.
Exorcisms and demonic possession doesn't fit into any worldview that is grounded in reality, because demons and demonic possessions don't exist.
They do not fit the reality that a modernistic, rationalist society sees. They do however fit the reality that a premodern, mythic and magic society sees. Everyone sees the world symbolically, and just because demons don't fit the symbolic language of a modern Western society, does not mean that they are not realities to those whose systems these are part of.
To them, your lack of demons indicates you are not grounded in reality, because reality to them includes them, just as their inclusion of demons makes them not grounded in reality to you because they don't exist in how you see reality. To those who believe demons are real, they become real. Reality is shaped by our beliefs about it, and becomes reflective of how we see and talk about it. whether that's a scientific reality or a mythic reality.
But exorcisms are known for sometimes being physically and mentally traumatizing, turning people into victims and corpses.
So can going under a modern surgeon's knife can do the same. So can any number of "cures" that people come up with, such as fad diets or any list of things we imagine will heal us of our woes. Think of all of it, from witch doctors to modern doctoring as a continuation of the same thing, fumbling and feeling our ways into the dark with ever growing systems of understanding. While modern science may be more successful in its "cures", the reality is its still quite primitive and superstition in its own right.
We pride ourselves a bit too much, when in a future time today will be seen just as quaint and primitive as the witch doctors of old.
Which is why, yeah, they do need to think more rationally because beliefe in superstitious entities and events just got another child killed.
No, it is not superstitious beliefs that got that child killed. Flatly no. It was a mental illness that did it.