The Catholic Church performs this kind of function chiefly by means of catechesis. By drawing the truth from the word of God and faithfully adhering to the secure expression of this word, catechesis strives to teach this word of God with complete fidelity. The function of catechesis, however, cannot be restricted to repetition of traditional formulas; in fact, it demands that these formulas be understood, and be faithfully expressed in language adapted to the intelligence of the hearers, using even new methods when necessary. The language will be different for different age levels, social conditions of men, human cultures, and forms of civil life.
Catechesis begins, therefore, with a rather simple presentation of the entire structure of the Christian message (using also summary or global formulas), and it presents this in a way appropriate to the various cultural and spiritual conditions of those to be taught. By no means, however, can it stop with this first presentation, but it must be interested in presenting the content in an always more detailed and developed manner, so that individuals among the faithful and the Christian community may arrive at an always more profound and vital acceptance of the Christian message, and may judge the concrete conditions and practices of Christian life by the light of revelation.
This task of catechesis, not an easy one, must be carried out under the guidance of the Magisterium of the Church, whose duty it is to safeguard the truth of the divine message, and to watch that the ministry of the word uses appropriate forms of speaking, and prudently considers the help which theological research and the human sciences can give. (Sacred Congregation for the Clergy, General Cathechetical Directory, 1971).