The content of the message of salvation is made up of parts that are closely interrelated, even though its revelation was given by God gradually, in limes past through the prophets, last of all in his Son (cf. Heb. 1, 1). Since the purpose of catechesis, as was said, consists in leading individual Christians and communities to a mature faith, it must take diligent care faithfully to present the entire treasure of the Christian message. This must surely be done according to the example of the divine pedagogy (cf. n. 33), but with the full store of revelation that has been divinely communicated being taken into account, 50 that the People of God may be nourished by it and live from lb. 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 b 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, 50 that individuals among the faithful and the Christian community may arrive al 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 duly il is to safeguard the truth of the divine message, and to walch thal the ministry of the word uses appropriate forms of speaking, and prudently considers the help which theological research and the human sciences can give.