The Catechism in Questions & Answers

441. What were the other important tasks of the Apostles?

An important task of the Apostles was to proclaim that Jesus Christ had been active among them, had died, and had resurrected from the dead (cf. Acts 13: 26-41; 17: 1-4). They fought against heresies that sought to deny these things (cf. 1 Corinthians 15: 3-8; 1 John 4: 1-6).