Sections 
THE CREED
The Creed is said in the Eucharistic celebration, after the homily, on Sundays and solemnities.
There is an inseparable link between the faith professed and the faith celebrated. We celebrate what we believe. Through the liturgical celebration, we enter into communion with the truths that we profess.
From the very beginning, the apostolic Church expressed and handed on her faith in brief formulas which were normative for all. Yet very early on, the Church also wanted to gather the essential elements of her faith into organic and articulated summaries, intended especially for candidates of Baptism:
“This synthesis of faith was not made to accord with human opinions, but rather what was of the greatest importance was gathered from all the Scriptures, to present the one teaching of the faith in its entirety. And just as the mustard seed contains a great number of branches in a tiny grain, so too this summary of faith encompassed in a few words the whole knowledge of the true religion contained in the Old and the New Testaments.” (St. Cyril of Jerusalem, Catech. illum. 5, 12)
These summaries also receive the name of “symbols.” They are also called "professions of faith" since they summarize the faith that Christians profess. They are called "creeds" on account of what is usually their first word in Latin: credo ("I believe"). They are also called "Symbols of Faith".
The Greek word “symbolon” means the half of a broken object, for example, a seal presented as a token of recognition. The broken parts were placed together to verify the bearer's identity. The symbol of faith, then, is a sign of recognition and communion between believers. Symbolon also means a “gathering, collection or summary.” A “symbol of Faith” is a summary of the principal truths of the faith and therefore serves as the first and fundamental point of reference for catechesis.
The first "profession of faith" is made during Baptism. The “Symbol of Faith” is first and foremost the baptismal creed. Since Baptism is given "in the name of the Father and of the Son and of the Holy Spirit" (Mt. 28:19), the truths of faith professed during Baptism are articulated in terms of their reference to the three persons of the Holy Trinity.
The Symbol, therefore, is divided in three parts: "the first part speaks of the first divine Person and the wonderful work of creation; the next speaks of the second divine Person and the mystery of His redemption of man; the final part speaks of the third divine Person, the origin and source of our sanctification" (Roman Catechism I, 1, 3.). These are "the three chapters of our [baptismal] seal" (St. Irenaeus, Dem. ap. 100: SCh 62, 170.).
Through the centuries many professions or symbols of faith have been articulated in response to the needs of the different eras: the creeds of the different apostolic and ancient Churches, e.g., the Quicumque, also called the Athanasian Creed; The professions of faith of certain Councils, such as Toledo, Lateran, Lyons, Trent; or the symbols of certain popes, e.g., the Fides Damasi or the Credo of the People of God of Paul VI.
None of the creeds from the different stages of the Church's life can be considered superseded or irrelevant. They help us today to attain and deepen the faith of all times by means of the different summaries made of it.
The Apostle’s Creed, or Symbol, is the shorter of the two creeds that we pray in the Mass. The Apostles' Creed is so called because it is rightly considered to be a faithful summary of the apostles' faith. It is the ancient baptismal symbol of the Church of Rome. Its great authority arises from this fact: it is "the Creed of the Roman Church, the See of Peter the first of the apostles, to which he brought the common faith".
The Nicene-Constantinopolitan, or simply Nicene, Creed is the longer of the two that we pray in Mass. It draws its great authority from the fact that it stems from the first two ecumenical Councils (in 325 and 381), as its name indicates. It is the result of a fusion of two creeds drawn up: one in the Council of Nicea (325) and the other in the Council of Constantinople (381). These councils defended Jesus’ true nature against two heresies: Arianism, which denied Christ’s divine nature, and Monophysitism -, which denied His human nature. Established on the tradition that had been passed down from the Apostles, the councils condemned both these heresies and declared that Jesus was true God and true man. This creed remains common to this day in all the great Churches of both the East and West.
Reciting the Creed with faith is a remembrance of our Baptism. To say the “I believe” with faith is to enter into communion with God the Father, Son and Holy Spirit and also with the entire Church that transmits the faith to us and in whose midst we believe: “This Creed is the spiritual seal, our heart's meditation and an ever-present guardian; it is, unquestionably, the treasure of our soul” (St. Ambrose, Expl. symb. I).
