19 The catholicity of the Church is manifested in the active joint responsibility and generous cooperation of all for the sake of the common good. The Church everywhere effects her universality by accepting, uniting and exalting in the way that is properly hers, with motherly care, every real human value. At the same time, she strives in every clime and every historical situation to win for God each and every human person, in order to unite them with one another and with him in his truth and his love. All individuals, all nations, cultures and civilizations have their own part to play and their own place in God's mysterious plan and in the universal history of salvation. This was the thought of the two holy Brothers: God "merciful and kind", "waiting for all people to repent,) that all may be saved and come to the knowledge of the Truth, ... does not allow the human race to succumb to weakness and perish, and to fall into the temptation of the enemy. But year by year and at every time he does not cease to lavish on us a manifold grace, from the beginning until today in the same way: first, through the Patriarchs and Fathers, and after them through the Prophets; and again through the Apostles and Martyrs, the just men and the Doctors whom he chooses in the midst of this stormy life".
Source: Slavorum Apostoli (Vatican.va)