system
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human
How to know the difference between existentialists

I believe that there are many philosophers that are considered as existentialists. 

Kierkegaard, Nietzsche, Jaspers, Camus, Sartre, Beauvoir, Merleau-Ponty, Heidegger (I think he is not, but our school's textbook says so), etc. 

I heard that even Dostoevsky and Kafka were kind of existentialist. 

I know that they are divided into big two category of christian existentialists, and atheistic existentialists.

But some says Nietzsche is nihilist or something, Camus is absurdist, and, yeah. 

Since I am not even an undergraduate but a highschool student, I don't have opportunities to get deeply about philosophy. 

I read some books such as The Myth of Sisyphus, The stranger, The Plague (Camus), Being and Nothingness, La nausée (Sartre) to try to understand them, but I ended up hardly undertanding them. 

I want to know differences between absurdism, nihilism, existentialism, and differences of those philosophers. 

Thank you!
gpt
>	But some says Nietzsche is nihilist or something, 

Only people who are wrong about Nietzsche say this (such people are common, particularly on the internet).*

>	I want to know differences between absurdism, nihilism, existentialism, and differences of those philosophers.

The typical introduction that is recommended is Sarah Bakewell’s *At the Existentialist Café.*

*EDIT: the point below about active vs passive nihilism, etc., is well-taken, but at this level you’d do best to just not associate Nietzsche’s position(s) with contemporary things that come to mind when one hears “nihilism”.