Unbeliever

[Jessica]

One who does not believe; an incredulous person; a
doubter; a skeptic.

[Marquetta]

The [Islamic] Quranic description of a [Jew] or Christian. Sometimes the word disbeliever is used in the same way but still has the same meaning. See also [Kafir]

[Dave Paprocki]

Someone who has no religious beliefs, or who does not follow a particular religion.

[Agnes]

a person who does not have any religious beliefs: