Synonyms of 'freethinker'
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An agnostic believes that it is not possible to know whether God exists or not. Compare atheist.
He was, if not an atheist, an agnostic.
If you refer to people as doubters, you mean that they have doubts about something, especially their religious or political system.
Doubters fear this may not be good news.
If one person refers to another as an infidel, the first person is hostile towards the second person because that person has a different religion or has no religion.
a holy war to drive the infidels out
Thesaurus for freethinker from the Collins English Thesaurus
a person who forms his or her ideas and opinions independently of authority or accepted views , esp in matters of religion