a person who does not believe in religion or who adheres to a religion other than one's own 无宗教信仰者;异教徒 [as plural noun the infidel]they wanted to secure the Holy Places from the infidel. 他们要保护圣地不受异教徒侵扰。
adjective
adhering to a religion other than one's own 异教的 the infidel foe. 异教敌人。
语源
late 15th cent.: from French infidèle or Latin infidelis, from in- 'not' + fidelis 'faithful' (from fides 'faith', related to fidere 'to trust'). The word originally denoted a person of a religion other than one's own, specifically a Muslim (to a Christian), a Christian (to a Muslim), or a Gentile (to a Jew)