The document outlines the four marks of the Catholic Church: one, holy, catholic, and apostolic, emphasizing their significance in Christian unity and doctrine. It discusses the church's unity as rooted in Christ, the holiness of the church despite containing sinners, the universal scope of its mission, and the apostolic foundation that underpins its authority. Additionally, it addresses the challenges of divisions within Christianity, urging the faithful to strive for greater unity and to heal the wounds of disunity.