What does "misbeliever" mean?

Someone who holds a bad or wrong belief; a heretic, an unbeliever.

What is a synonym for "misbeliever"?

Common synonyms include: albigensian, antinomian, arian, cathar, dissenter, dissident.

/mɪsbɪˈlivɚ/ noun

noun ·Rare ·Advanced level

Noun

1
Someone who holds a bad or wrong belief; a heretic, an unbeliever.
"We are placed in the country […] where we feare the menaces wherewith she threatneth all mis-beleevers, or follow her promises."
2
a person who holds religious beliefs in conflict with the dogma of the Roman Catholic Church wordnet

"We are placed in the country […] where we feare the menaces wherewith she threatneth all mis-beleevers, or follow her promises."

From Middle English misbilevere, equivalent to misbelieve + -er.