Credo

Credo (pronounced kree-doh or krey-doh)

(1) The Apostles' Creed or the Nicene Creed (often initial capital letter).

(2) A musical setting of the creed, usually of the Nicene Creed (often initial capital letter).

(3) Any creed or formula of belief; doctrine, tenet, philosophy.

(4) Any formal or authorized statement of beliefs, principles, or opinions

1150–1200: From the Middle English credo (the Creed in the Church service), from the Latin crēdō (the first person singular present indicative of credere (to believe" (literally "I believe")), the first word of the Apostles' and Nicene Creeds in Latin (Credo in Deum Patrem omnipotentem, Creatorem caeli et terrae).  The Latin crēdō was from the Proto-Italic krezdō, from the primitive Indo-European compound kerd-dhe (literally "to place one's heart" (ie to trust, believe)), a compound phrase of oblique case form of ḱḗr (heart), also the root of the Latin cor- & deh- (to put, place, set) and the Latin faciō).  It was cognate with the Welsh credu (I believe), the Sanskrit श्रद्दधाति (śrad-dhā) (to trust, believe; faith, confidence, devotion) and the Old Irish creitid (believes (verb)).  In English the form was soon nativized as creed while the general sense of a "formula or statement of belief" emerged in the late sixteenth century.  One of the more quoted phrases from the epic poem The Aeneid (29-19 BC) by the Roman poet Virgil (Publius Vergilius Maro (70–19 BC)) was experto crede ("take it from one who knows"), the construct the dative singular of expertus + the imperative singular of credere (to believe).  Credo is a noun; the noun plural is credos.

Intended as a basic, succinct statement of the faith, the Apostles’ Creed was structured according to the fundamental belief in the Trinity and the function particular to each of the three Persons:  The Father & creation; the Son & redemption; and the Holy Spirit & sanctification.  It was relatively short and simple, able to be memorized and recited even by the illiterate, an important tradition in times of persecution when it was part of the disciplina arcana (discipline of the secret) to be remembered and passed on orally as a protection against attack.

The Nicene Creed was produced by the Council of Nicea I (325) which was convoked to combat the heresy of Arius (who denied the divinity of Christ).  The Council wished firmly to confirm Christ was consubstantial (one in being) with God, sharing the same divine nature; begotten, not made or created; and that Mary conceived by the power of the Holy Spirit, and through her, Jesus Christ, true God, became also true man. 

Later, at the Council of Constantinople (381), the Church again not only affirmed its condemnation of Arianism but also of the Pneumatomachi (killers of the Spirit) who not only denied the divinity of Jesus but also the divinity of the Holy Spirit.  Thus the creed was expanded to clearly define the divinity of the Holy Spirit, adapting the text written in 374 by Saint Epiphanius of Salamis (circa 310-403).  This creed, officially entitled the Nicene-Constantinopolitan Symbol, was introduced into the Mass circa 500.

Lindsay Lohan's daily skincare credo, the meaning enhanced in the modern way with emojis.