What is the Catholic Church
The Church Is One, Holy, Catholic, and Apostolic
811 “This is the sole Church of Christ, which in the Creed we profess to be one, holy, catholic and apostolic.” These four characteristics, inseparably linked with each other,indicate essential features of the Church and her mission. The Church does not possess them of herself; it is Christ who, through the Holy Spirit, makes his Church one, holy, catholic, and apostolic, and it is he who calls her to realize each of these qualities.
812 Only faith can recognize that the Church possesses these properties from her divine source. But their historical manifestations are signs that also speak clearly to human reason. As the First Vatican Council noted, the “Church herself, with her marvelous propagation, eminent holiness, and inexhaustible fruitfulness in everything good, her catholic unity and invincible stability, is a great and perpetual motive of credibility and an irrefutable witness of her divine mission.”
From the Catechism of the Catholic Church