Faith
From the Compendium Catechism:

25. How does man respond to God who reveals himself?

Sustained by divine grace, we respond to God with the obedience of faith, which means the full surrender of ourselves to God and the acceptance of his truth insofar as it is guaranteed by the One who is Truth itself.

26. Who are the principal witnesses of the obedience of faith in the Sacred Scriptures?

There are many such witnesses, two in particular: One is Abraham who when put to the test “believed in God” (Romans 4:3) and always obeyed his call. For this reason he is called “the Father of all who believe” (Romans 4:11-18). The other is the Virgin Mary who, throughout her entire life, embodied in a perfect way the obedience of faith: “Let it be done to me according to your word” (Luke 1:38).

27. What does it mean in practice for a person to believe in God?

It means to adhere to God himself, entrusting oneself to him and giving assent to all the truths which God has revealed because God is Truth. It means to believe in one God in three Persons, Father, Son, and Holy Spirit.

28. What are the characteristics of faith?

Faith is the supernatural virtue which is necessary for salvation. It is a free gift of God and is accessible to all who humbly seek it. The act of faith is a human act, that is, an act of the intellect of a person - prompted by the will moved by God - who freely assents to divine truth. Faith is also certain because it is founded on the Word of God; it works “through charity” (Galatians 5:6); and it continually grows through listening to the Word of God and through prayer. It is, even now, a foretaste of the joys of heaven.

29. Why is there no contradiction between faith and science?

Though faith is above reason, there can never be a contradiction between faith and science because both originate in God. It is God himself who gives to us the light both of reason and of faith.

“I believe, in order to understand; and I understand, the better to believe.”(Saint Augustine)

30. Why is faith a personal act, and at the same time ecclesial?

Faith is a personal act insofar as it is the free response of the human person to God who reveals himself. But at the same time it is an ecclesial act which expresses itself in the proclamation, “We believe”. It is in fact the Church that believes: and thus by the grace of the Holy Spirit precedes, engenders and nourishes the faith of each Christian For this reason the Church is Mother and Teacher.

“No one can have God as Father who does not have the Church as Mother.”(Saint Cyprian)

31. Why are the formulas of faith important?

The formulas of faith are important because they permit one to express, assimilate, celebrate, and share together with others the truths of the faith through a common language.

32. In what way is the faith of the Church one faith alone?

The Church, although made up of persons who have diverse languages, cultures, and rites, nonetheless professes with a united voice the one faith that was received from the one Lord and that was passed on by the one Apostolic Tradition. She confesses one God alone, Father, Son, and Holy Spirit, and points to one way of salvation. Therefore we believe with one heart and one soul all that is contained in the Word of God, handed down or written, and which is proposed by the Church as divinely revealed.

33. What are the symbols of faith?

The symbols of faith are composite formulas, also called “professions of faith” or “Creeds”, with which the Church from her very beginning has set forth synthetically and handed on her own faith in a language that is normative and common to all the faithful.

34. What are the most ancient symbols (professions) of faith?

The most ancient symbols of faith are the baptismal creeds. Because Baptism is conferred “in the name of the Father, and of the Son, and of the Holy Spirit” (Matthew 28:19), the truths of faith professed at Baptism are articulated in reference to the three Persons of the Most Holy Trinity.

35. What are the most important symbols of the faith?

They are the Apostles' Creed which is the ancient baptismal symbol of the Church of Rome and the Nicene-Constantinopolitan Creed which stems from the first two ecumenical Councils, that of Nicea (325 A.D.) and that of Constantinople (381 A.D.) and which even to this day are common to all the great Churches of the East and the West.