9
cynic(noun, radical, revolutionary, critic, detractor)
9
atheist(noun, adjective, person, view, disbelieve)
8
doubter
7
unbeliever(noun, radical, revolutionary, critic, detractor)
6
agnostic(noun, adjective)
5
dissenter(noun, radical, revolutionary, detractor, subversive)
5
heathen(noun, adjective)
5
questioner(noun, radical, revolutionary, critic, detractor)
4
denier
4
doubting Thomas
4
skeptic
3
disbeliever(noun, doubter)
3
heretical
3
infidel(noun, adjective)
3
nullifidian(noun, adjective)
3
pagan(noun, adjective)
2
heretic(noun, adjective, radical, revolutionary, detractor)
2
naysayer
1
apostate
1
apostatical
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APASmart Define. (2016). sceptic thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/sceptic/thesaurus/synonyms
ChicagoSmart Define. 2016. "sceptic thesaurus" https://smartdefine.org/sceptic/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2016, sceptic thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/sceptic/thesaurus/synonyms>.
MLASmart Define. "sceptic thesaurus" 20 February 2016. Web. 20 September 2026. <https://smartdefine.org/sceptic/thesaurus/synonyms>