The origins of the word Infidel date to the late 15th century, deriving from the French infidèle or Latin īnfidēlis, from in- "not" + fidēlis "faithful" (from fidēs "faith", related to fīdere 'to trust'). The word originally denoted a person of a religion other than one's own, specifically a Christian to a Muslim, a Muslim to a Christian, or a Gentile to a Jew. Later meanings in the 15th century include "unbelieving", "a non-Christian" and "one who does not believe in religion" (1527).
- 1: one who is not a Christian or who opposes Christianity
- 2a : an unbeliever with respect to a particular religion
- b : one who acknowledges no religious belief
- 3: a disbeliever in something specified or understood
Infidel (literally "one without faith") is a term used in certain religions, especially Christianity or Islam, for one who has no religious beliefs, or who doubts or rejects the central tenets of the particular religion.
Infidel is an ecclesiastical term in Christianity around which the Church developed a body of theology that deals with the concept of infidelity, which makes a clear differentiation between those who were baptized and followed the teachings of the Church versus those who are outside the faith. The term infidel was used by Christians to describe those perceived as the enemies of Christianity. When applied to non-monotheists, the usage of the word is similar to the appellations heathen or pagan. As such, the term infidel has often been applied to atheists, whose disbelief is viewed negatively in both Christianity and Islam.
After the ancient world the concept of otherness, an exclusionary notion of the outside by societies with more or less coherent cultural boundaries, became associated with the development of the monotheistic and prophetic religions of Judaism, Christianity and Islam. The conception of infidelity as a theological condition is a result of their strict conformity to monotheism, as well as their rejection and condemnation of pagan rites.