“Primary proclamation is addressed to non-believers and those living in religious indifference. Its functions are to proclaim the Gospel and to call to conversion. 

Catechesis, "distinct from the primary proclamation of the Gospel", promotes and matures initial conversion, educates the convert in the faith and incorporates him into the Christian community. The relationship between these two forms of the ministry of the word is, therefore, a relationship of complementary distinction. Primary proclamation, which every Christian is called to perform, is part of that "Go" which Jesus imposes on his disciples: it implies, therefore, a going-out, a haste, a message. 

Catechesis, however, starts with the condition indicated by Jesus himself: "whosoever believes", whosoever converts, whosoever decides.” -General Directory of Catechesis 61