What is the X in X-mas?
mid-12c., "benevolence for the poor," from Old French charité "(Christian) charity, mercy, compassion; alms; charitable foundation" (12c., Old North French carité), from Latin caritatem (nominative caritas) "costliness, esteem, affection" (in Vulgate often used as translation of Greek agape "love" -- especially Christian love of fellow man -- perhaps to avoid the sexual suggestion of Latin amor), from carus "dear, valued," from PIE *karo-, from root *ka- "to like, desire" (see whore (n.)).
Vulgate also sometimes translated agape by Latin dilectio, noun of action from diligere "to esteem highly, to love" (see diligence).
Wyclif and the Rhemish version regularly rendered the Vulgate dilectio by 'love,' caritas by 'charity.' But the 16th c. Eng. versions from Tindale to 1611, while rendering agape sometimes 'love,' sometimes 'charity,' did not follow the dilectio and caritas of the Vulgate, but used 'love' more often (about 86 times), confining 'charity' to 26 passages in the Pauline and certain of the Catholic Epistles (not in I John), and the Apocalypse .... In the Revised Version 1881, 'love' has been substituted in all these instances, so that it now stands as the uniform rendering of agape. [OED]Sense of "charitable foundation or institution" in English attested by 1690s.
(1 Cor. 13), the rendering in the Authorized Version of the word which properly denotes love, and is frequently so rendered (always so in the Revised Version). It is spoken of as the greatest of the three Christian graces (1 Cor. 12:31-13:13).
in Christian thought, the highest form of love, signifying the reciprocal love between God and man that is made manifest in unselfish love of one's fellow men. St. Paul's classical description of charity is found in the New Testament (I Cor. 13). In Christian theology and ethics, charity (a translation of the Greek word agape, also meaning "love") is most eloquently shown in the life, teachings, and death of Jesus Christ. St. Augustine summarized much of Christian thought about charity when he wrote: "Charity is a virtue which, when our affections are perfectly ordered, unites us to God, for by it we love him." Using this definition and others from the Christian tradition, the medieval theologians, especially St. Thomas Aquinas, placed charity in the context of the other Christian virtues and specified its role as "the foundation or root" of them all