nihilism
n//ˈnaɪ.(h)ɪ.lɪz.m̩//nihilism
(usually, uncountable) The rejection of, or opposition to, religious beliefs, (inherent or objective) moral principles, legal rules, etc., often due to the view that life is meaningless (sense 1).
(countable, uncountable, philosophy) A doctrine grounded on the negation of one or more meaningful aspects of life; in particular, the view that nothing in the world actually exists.