The function of Catholic catechesis is to teach (catechize or catechise) the faith of the Catholic Church by both word and example. A catechist is a person appointed to perform this function. The Church's Directory for Catechesis states that faith must be "known, celebrated, lived, and turned into prayer" in a personal and total encounter of the heart, mind and senses with Christ. St. John Paul II describes the aim of catechesis as putting "people not only in touch but in communion, in intimacy, with Jesus Christ."

The Second Vatican Council identified catechetical instruction as the "foremost" means by which the Church "enlightens and strengthens the faith, nourishes life according to the spirit of Christ, leads to intelligent and active participation in the liturgical mystery and gives motivation for apostolic activity".

Papal audiences often contain teaching presentations referred to as "catechesis", for example Pope Francis' audiences incorporated "catechesis", and Pope Leo XIV's general audiences in August 2025 incorporated his "continuing catechesis on the Jubilee theme of 'Christ our Hope'".

The Directory for Catechesis describes the catechist as "a Christian who receives a particular calling from God that, when accepted in faith, empowers him for the service of transmission of the faith and for the task of initiating others into the Christian life".

To catechize means to teach: more specifically, to teach by word of mouth. Prior to the Second Vatican Council, the chief catechists at the parish level were priests, religious brothers or sisters. Since the late 20th century, particularly in Europe and the Americas, increasingly the role of the parish catechist has been undertaken by the lay people. In addition to activities in the parish, catechizing also takes place in Catholic schools through more formal classes as part of the curriculum.

Catechists are often deployed to work with candidates who are preparing for the sacraments of Reconciliation, First Holy Communion, Confirmation and Baptism (after completing the Rite of Christian Initiation of Adults, or RCIA). Various age-appropriate religious education texts and materials are used for instruction in addition to the Catechism of the Catholic Church.

Catechists have always been of particular importance in large geographical parishes, such as in Africa, where priests have historically only been able to visit different parts of their parish periodically. In the priest's absence, the parish catechist takes on the role of being the main teacher of the faith in that parish. As such they are afforded a particular place of honor within their parish community.

The General Instruction of the Roman Missal allows for institution of catechists should any Episcopal Conference determine that the role is required.^{[citation needed]}