The document discusses the four marks of the Catholic Church: that it is one, holy, catholic, and apostolic. It explains each mark in detail. The Church is one because it has one founder and source in Christ and the Holy Spirit makes believers one. It is holy because Christ sanctifies it and calls believers to holiness through love. It is catholic because it has a universal mission and message for all people. It is apostolic because it was founded by Christ and the apostles and their teaching is continued through the bishops. The marks challenge the Church to continuously strive to more fully embody unity, holiness, catholicity, and apostolicity.