Sense of "freethinker" is first recorded 1560s, from French libertin (1540s) originally the name given to certain pantheistic Protestant sects in France and the Low Countries. This sense partakes more of liberty and liberal than of the classical meaning (in Old French, libertin meant "Saracen slave converted to Christianity"). Meaning "dissolute or licentious person, man given to indulgence of lust" is first recorded 1590s; the darkening of meaning being perhaps due to misunderstanding of Latin libertinus in Acts vi:9. For "condition of being a libertine" 17c English tried libertinage; libertinism (from French libertinisme).
"act of setting free from restraint or confinement," early 15c., liberacion, from Old French libération and directly from Latin liberationem (nominative liberatio) "a setting or becoming free," noun of action from past-participle stem of liberare "to set free," from liber "free" (see liberal (adj.)).
Liberation theology (1969) translates Spanish teologia de la liberación, coined 1968 by Peruvian priest Gustavo Gutiérrez (b. 1928). In late 19c. British history, liberationism, liberationist are in reference to the movement to disestablish the Church, from the Liberation Society, devoted to the freeing of religion from state patronage and control.