Regarding the sources of catechetical instructions the Second Vatican Council states; “it should be based on holy scripture, tradition, liturgy and on the teaching authority and life of the Church” . Actually all these sources are the expressions of the revealed Word of God which is the living source for Catechesis.
1. Word of God
Sacred Scripture is one of the most important sources of the faith formation. Faith formation is primarily a ministry of the Word and Sacred Scripture is the deposit of the Word of God which is entrusted to the Church.
2. Liturgy
Liturgy is another main source of faith formation. The liturgical celebration of the Christian community is presented as the proclamation of the death and resurrection of Christ, which is the core of the Gospel (1 Cor. 11:26). The leader of the liturgical community is said to be proclaiming the Gospel in the course of the liturgical action (Rom. 15:16). Hence liturgy or Christian worship is not a ritual act, but a ministry of the Word. Although the whole liturgical celebration is a moment in the process of the faith formation of the Christian, there are certain specific moments in the celebration during which liturgy becomes a powerful expression of the ministry of the word, namely homily:

3.Sacred Tradition and Magisterium
Sacred tradition and magisterium is another important source of the faith formation. Sacred tradition is the living and lived faith of the Church. “Sacred Tradition transmits in its entirety the Word of God which was entrusted to the apostles by Christ the Lord and the Holy Spirit” .
4. Witness
Witness is another source of faith formation. The life of Jesus is the witness of heavenly Father. The Holy Spirit will bear witness, “He will bear witness to me; and you also are witnesses” (Jn. 15: 26-27). John Baptist bears witness to Christ in his preaching, by his Baptism of conversion, and through his martyrdom (Lk. 1:17).
Agents of Faith Formation
The Church is the basic agent of faith formation. Besides the Church as a whole, there are specific persons in the Church who participate in a special way in the ministry of faith formation. They are mainly the bishops, priests, parents, the religious, and the lay catechists.
5.The Bishop
The bishop is the chief faith formator of the diocese, the one providing all that is required and involving others in this ministry. “Among the principal duties of Bishops, that of preaching the Gospel excels”.
6. The Priests
The Second Vatican Council called the priests “instructors of the people in the faith.” St. John Paul II says: “There is no better way for you to be such instructors than by devoting your best efforts to the growth of your communities in the faith. Whether you are in charge of a parish, or chaplains to primary or secondary schools or universities, the Church expects you to neglect nothing with a view to a well-organized and well-oriented catechetical effort.”
7. The Men and Women Religious
The religious are also called in a special way to assist the ministry of faith formation. “In a special way the Church calls upon those in consecrated life to catechetical activity and wishes that religious communities dedicate themselves as much as possible of what ability and means they have to the specific work of Catechesis.
8. The Lay Catechists
There are a good number of lay catechists rendering whole – hearted service in the field of faith formation in the Church. The Church considers their service with great respect and recognizes them as special ministers of the community.
9. The Lay Association Leaders
The lay leaders are secular in nature and they can reach out to areas which official ministers cannot reach. Their presence in all places is itself a faith formation through testimony. They are called to live a continuous faith formation life with their Words and actions.
10. The Parents
The Parents are the first and primary formators of faith especially to the infants and children. The witness of life given by the parents in the context of the family helps the infants and children to imbibe the faith experience of the Church. The role of parents in the religious awakening of their children in the family is an irreplaceable one.