A person who works or advocates for liberation(noun)
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Use "liberationist" in a sentence
"Democracy is the god that failed to accomplish its ostensible goals everywhere the U.S. has intervened but the real objective of our 'liberationist' foreign policy is well on the way to being achieved"
"It promises to be quite the laudatory affair in honor of this "liberationist" movement in theology."
"1988 - In his "Why Organize?" essay, Obama planned to politically organize "liberationist" black churches."