x1 is a doctrine/theory/system/philosophy/practice/action/habit/mindset/ism characterized by belief/tendency/action/idea x2 (abstraction), and incidentally is practiced by x3 (and possibly others).
Not necessarily derogatory. "Materialism" (any sense) is a type of ism as much as racism, whataboutism, or Trumpism is. This word is meant to be a calque of the English word "ism". Closely related to ".ismo".