Citations from: “Catechism of the Catholic Church”:
https://www.vatican.va/archive/ENG0015/_INDEX.HTM
Part One: The Profession Of Faith, Section 2, Chapter 3, Article 9 , Paragraph 3
https://www.vatican.va/archive/ENG0015/__P29.HTM
Paragraph 3. The Church Is One, Holy, Catholic, And Apostolic
819 "Furthermore, many elements of sanctification and of truth" 273 are found outside the visible confines of the Catholic Church: "the written Word of God; the life of grace; faith, hope, and charity, with the other interior gifts of the Holy Spirit, as well as visible elements." 274 Christ's Spirit uses these Churches and ecclesial communities as means of salvation, whose power derives from the fullness of grace and truth that Christ has entrusted to the Catholic Church. All these blessings come from Christ and lead to him,275 and are in themselves calls to "catholic unity." 276
Toward unity
820 "... Jesus himself prayed at the hour of his Passion, and does not cease praying to his Father, for the unity of his disciples: "That they may all be one. As you, Father, are in me and I am in you, may they also be one in us, . . . so that the world may know that you have sent me." 278 The desire to recover the unity of all Christians is a gift of Christ and a call of the Holy Spirit .279
821 Certain things are required in order to respond adequately to this call: