From the Catechism of the Catholic Church, Simplified
Receiving Faith from Others (166-167)
Although faith is a personal act, the believer does not act in isolation. Having received human life from others, the believer also receives faith from others, and passes it on to others.
The Apostles Creed begins with "I believe" ( the act of the individual believer). The Nicene Creed begins with "We believe," the faith of the Church expressed by all at Mass.
The Church's Faith (168-169)
First, the Church believes and professes the Lord. Later, the person (won over by the Church) can say, "I believe." "What do you ask of God's Church?" asks the baptismal liturgy. The answer is "faith" which offers "eternal life."
The Church is not the author of salvation. This comes from God alone. We do not believe in the Church as if she is the author of our salvation. We believe that through the Church we receive our salvation.
The Need for Formulas (170-171)
Also, we do not believe in the formulas of the Creeds but in the realities expressed by these formulas. However, the formulations help us to approach these realities, to live the faith.
The Church guards Christ's own words, hands on the apostolic confessions of faith, and teaches her children the "language of faith."
Transmitting the One Faith (172-175)
Through all these centuries and cultures, the Church has transmitted one faith, believing that all people have "one Lord, one faith, one Baptism" (Eph 4:4).
Having received faith from the apostles, the Church hands on this faith with a unanimous voice.
Though languages differ throughout the world, the content of the Tradition is one and the same. One and the same way of salvation appears throughout the whole world (St. Irenaeus).
"We guard with care this faith because this deposit of a great price causes the very vessel that contains it to be renewed" (St. Irenaeus).