31 Various types of the apostolate demand also a specially suitable formation. a) In regard to the apostolate for evangelizing and sanctifying men, the laity must be specially formed to engage in conversation with others, believers, or non-believers, in order to manifest Christ's message to all men. Since in our times, different forms of materialism are spread far and wide even among Catholic, the laity should not only learn doctrine more diligently, especially those main points which are the subjects of controversy, but should also exhibit the witness of an evangelical life in contrast to all forms of materialism. b) In regard to the Christian renewal of the temporal order, the laity should be instructed in the true meaning and value of temporal things, both in themselves and in relation to all the aims of the human person. They should be trained in the right use of things and the organization of institutions, attentive always to the common good in line with the principles of the moral and social teaching of the Church. Laymen should above all learn the principles and conclusions of the social doctrine so as to become capable of working for the development of this doctrine to the best of their ability and of rightly applying these same principles and conclusions to individual cases. c) Since the works of charity and mercy express the most striking testimony of the Christian life, apostolic formation should lead also to the performance of these works so that the faithful may learn from childhood on to have compassion for their brethren and to be generous in helping those in need.
Source: Apostolicam Actuositatem (Vatican.va)