An apostle is one who is sent. The Church is called “apostolic” because it holds the faith of the first apostles sent by Christ. In continuity with them, the Church is likewise sent by Christ to proclaim the Gospel and to make disciples throughout the whole world.
The Church is holy because the Holy Spirit dwells in it and sanctifies its members, setting them apart to God in Christ and calling them to moral and spiritual holiness of life.
The Church is one because all its members form the one Body of Christ, having “one Lord, one faith, one baptism, one God and Father of all." The Church is called to embody this unity in all relationships between believers.
The Nicene Creed expands upon the Apostles’ Creed to list four characteristics of the Church: it is “one, holy, catholic, and apostolic.”
I can rely on Jesus always to be present with me by the Holy Spirit as he promised, and I should always look to him for help as I seek to serve him.