One who is yet undecided as to what is true; one who is
looking or inquiring for what is true; an inquirer after facts or
reasons.

A doubter as to whether any fact or truth can be certainly
known; a universal doubter; a Pyrrhonist; hence, in modern usage,
occasionally, a person who questions whether any truth or fact can be
established on philosophical grounds; sometimes, a critical inquirer,
in opposition to a dogmatist.

A person who doubts the existence and perfections of God,
or the truth of revelation; one who disbelieves the divine origin of
the Christian religion.

Alt. of Skeptical