infidel

Infidel is a fifteenth-century Latinate borrowing that carries the whole history of European religious polemic in its five syllables.‍​‍​‍​‍​‍​‍​‌​‌​‌​‌​‍​‌​‌​‌​‍​‌​‍​‌​‍​‌​‍​‍​‌​‌​‍​‍​‌​‌​‌​‌​‌​‌ Built from the Latin negative prefix in- ("not") and fidelis ("faithful"), it descends from the noun fides ("faith, trust, loyalty"), which itself traces to the Proto-Indo-European root *bʰeydʰ- ("to trust, to have confidence in"). The same root produced Greek peithein ("to persuade"), Gothic beidan ("to wait, to trust"), and an enormous family of English fid- words — fidelity, confide, fiducial, fiance, perfidy, affidavit, bona fide. English borrowed "infidel" around 1460 through Old French infidele, at a moment when Europe was still processing the cultural memory of the Crusades, and the word's first uses were narrowly theological: an infidel was a Muslim. The word's history since has been a slow widening: from the religious boundary between Christian and non-Christian, to the internal boundary between Protestant and Catholic, to the secular boundary between believer and unbeliever.

The English word infidel comes from Latin infidelis, meaning unfaithful or unbelieving. It is formed from the negative prefix in- ("not") and fidelis ("faithful"), built on fides, the Roman word for faith, trust and loyalty. Fides in turn descends from the Proto-Indo-European root *bʰeydʰ-, "to trust, to have confidence in", the same seed that produced Latin foedus (covenant), Greek peithein (to persuade) and Gothic beidan (to wait, to trust). The PIE root carried a semantic core of relational trust — the kind of confidence that binds one party to another — which later branches specialised in different directions: Greek toward persuasion, Germanic toward waiting and expectation, Latin toward loyalty and sworn bond. Infidel sits at the negative pole of that Latin specialisation.

English borrowed the word around 1460 through Old French infidele, at a moment when Europe was still processing the cultural memory of the Crusades. The earliest citations cluster in anti-Turkish polemic following the fall of Constantinople in 1453, a civilisational shock that flooded European vernaculars with words for the religious other. In that first English sense it was narrowly theological: an infidel was a Muslim — someone outside the Christian covenant of faith. Tyndale's New Testament of 1526 uses "infidel" at 1 Timothy 5:8 and 1 Corinthians 7:15, translating Greek apistos ("unbelieving"), and the King James Bible of 1611 preserves it there, anchoring the word in the Protestant English vocabulary of religion.

Yet the accusation was never one-sided. Muslim writers used the Arabic kafir, "one who conceals the truth," for Christians in exactly the same structural way. Each community defined itself as the faithful and the other as the unbelieving. Medieval Hebrew goy and min, Byzantine Greek apistos and asebes, and Latin infidelis all played analogous boundary-making roles — the vocabulary of any monotheism needs a word for those outside its compact, and that word is always charged. In the Crusader chronicles of Fulcher of Chartres and Villehardouin, "infideles" is the standard term for Muslims; in Mamluk and Ottoman documents, kuffar (plural of kafir) was the standard term for Christians. The symmetry is historically instructive.

From the Reformation onward the word widened. Protestants and Catholics applied it to each other in a deliberate inflation of the term: Luther called papal Rome "the infidel," the Council of Trent returned the charge, and by the sixteenth century religious polemic had made "infidel" a movable insult. By the Enlightenment it was being turned inward, against deists, freethinkers and atheists within Christian Europe. Tom Paine's The Age of Reason (1794) was attacked as "infidel" literature and the adjective settled on Paine himself. In nineteenth-century America, "infidel" became the standard slur against Robert Ingersoll and other freethinkers, and "the infidel tradition" was by then a self-conscious label adopted by some of the accused. This was the word's third register: no longer Muslim, no longer confessional enemy, but doubter within.

The fid- family is everywhere in English — fidelity, confide, confident, diffident, perfidy, fiduciary, federal (from foedus, a covenant), fiance (the "trusted one," promised in faith), affidavit (he has pledged in faith), bona fide (in good faith). Fiducia in Latin meant the trust placed in someone, particularly in legal and religious bonds; confidere was "to trust thoroughly"; diffidere was "to distrust." English inherited the whole semantic toolkit. Seen against that family, infidel is simply its shadow: the one who has fallen outside the circle of trust. Diffident, despite looking harsher, is a milder cousin — it means "lacking confidence" in oneself; infidel aims the same prefix at the relation with another.

The PIE root *bʰeydʰ- is widely attested. Beyond Latin fides, it produced Greek peithein ("to persuade") and its derivative peithomai ("I am persuaded, I obey"), preserved in the English philosophical loan pistis ("faith") via late Greek. The Germanic descendants include Old English bidan ("to wait, remain, endure") — the source of modern English abide, bide, and the now-obsolete bidden in its older sense. Gothic beidan and Old Norse biota complete the Germanic picture. The semantic thread that connects "trust," "persuade," and "wait" is not obvious to moderns but sits at the root: to wait faithfully for someone is to trust them, and to be persuaded by someone is to extend them your trust. Infidel, as a word, stands at the far end of all these possibilities — the trust withheld, the persuasion refused, the bond of fidelity not entered into.

In modern English, "infidel" has fallen out of serious use. It survives in historical writing, in religious polemic where its old heat is being deliberately invoked, and in the fiction and film vocabulary of Crusades-era settings. Contemporary discussions of religious boundary use more neutral terms — "non-believer," "unbeliever," "outsider." The word's rehabilitation, if any, has been in ironic self-application by some secularists who adopt "infidel" as a point of pride, following the pattern of Paine and Ingersoll. It is unlikely to return to wide currency; the structure of pluralist societies does not favour words that sort people into inside and outside with such medieval sharpness.