per wiki............
Etymology
First used in Middle English circa 1460 (adjective, noun), from the Middle French infidèle, and from Latin infidelis "unfaithful," later "unbelieving," In the 15c. meaning "a non-Christian" (especially a Saracen); later "one who does not believe in religion" (1526). Also used to translate Arabic kafir, from a root meaning "to disbelieve, to deny," strictly referring to all non-Muslims but virtually synonymous with "Christian"; hence, from a Muslim or Jewish point of view, "a Christian".[5]
In Christianity
In Roman Catholic Christianity, the term "infidel" is an ecclesiastical term referring to one who does not believe in the divinity of Jesus or one who has not been baptized. A heretic, in contrast, is an individual who believes in the divinity of Jesus, but also knowingly holds beliefs that contradict Catholic dogma, while a schismatic is an individual who does not hold beliefs contrary to Catholic dogma, but denies the authority of the Catholic Church.[7]
In Islam
Main article: kafir
In Islam, the Arabic word kafir (كافر) refers to a person who inwardly or outwardly denies Allah and/or the Islamic prophet Muhammad. Because the term is considered derogatory,[8] Muslim scholars discourage its usage due to the Quran's command to use kind words.[9] It is even a punishable offence to use this term against a Jew or a Christian, under Islamic law.[8]
I do not mind to be called infidel by any religious group I am indeed "not fidel" to. It is just an honest assessment of my status from their point of view.
But I do mind, however, being killed or even assigned a second class citizen status, because I am infidel/kafir/black/white/readhead/big/short/rich/poor for any religious or non-religious group.
~ Etymology of the term " Infidel " ~ an example of religion & cultural diversity in civilization gone bad / mad..............
(aka - the birthing of acquired terrorism)