How to say "atheist" in Japanese

• 無神論者むしんろんしゃ
  nounThe straightforward term for an atheist as a person — literally 'a person of the no-god theory' — someone who holds or asserts that no god exists; it fits discussion of religion, philosophy, or belief.
  無神論むしんろん者しゃが司教しきょうの説明せつめいをあざけった。↗

  The irreligious scoffed at the bishop's interpretation.
• 無神者むしんじゃ
  nounAlso 'atheist' as a person, literally 'a no-god person'; it is less common, and for this sense 無神論者 is the safer choice, so this word is seldom the one you want.
• 無信心むしんじん
  noun, na-adjectiveChiefly a noun for unbelief, irreligion, or atheism — an absence of faith — rather than for a person; as a label for an individual atheist it is marginal, and 無神論者 is the word to use.

For 'atheist' as a person, use 無神論者; 無神者 is a less common synonym with the same person sense; 無信心 is really the noun for unbelief, irreligion, or atheism itself, not for the person.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 無神論者むしんろんしゃatheist
• 無神者むしんじゃatheist
• 無信心むしんじんirreligion