Yeah I'll admit that I have a broad definition. In particular I think the older strands that are indebted to theology are actually more useful than Camus. Kierkegaard or Augustine, in their decentering of man in the face of god, are more useful for materialist politics than :LIB: thinkers like Camus that want to simply put man in the place of god. Put another way, the kind of existentialism that I'm interested in takes as a starting point the idea that the individual is not an autonomous sovereign subject in control of its actions but instead embedded in the world and history. Given the fact we are thrown into this world without asking for it, this kind of existentialism is basically interested in how to act when you're not sovereign. Augustine's idea of bondage to sin is maybe the root of this kind of thinking.

For materialist politics this isn't to say we're all chained and screwed, but instead to reflect the reality that individual action is always incomplete and that it's only in collective action that we gain real power (this bit is something that Arendt talks about in the human condition)