unbeliever russian

• безбо́жник

  atheist, unbeliever, godless person

  impious person, blasphemer, sinner

• безбо́жница

  atheist (female), unbeliever (female)

• неве́рующая

  unbeliever, non-believer

• малове́рка

  skeptic, doubter, unbeliever, person of little faith