12 The same Dogmatic Constitution listed at length "the elements of sanctification and truth" which in various ways are present and operative beyond the visible boundaries of the Catholic Church: "For there are many who honour Sacred Scripture, taking it as a norm of belief and of action, and who show a true religious zeal. They lovingly believe in God the Father Almighty and in Christ, Son of God and Saviour. They are consecrated by Baptism, through which they are united with Christ. They also recognize and receive other sacraments within their own Churches or Ecclesial Communities. Many of them rejoice in the episcopate, celebrate the Holy Eucharist, and cultivate devotion towards the Virgin Mother of God. They also share with us in prayer and other spiritual benefits. Likewise, we can say that in some real way they are joined with us in the Holy Spirit, for to them also he gives his gifts and graces, and is thereby operative among them with his sanctifying power. Some indeed he has strengthened to the extent of the shedding of their blood. In all of Christ's disciples the Spirit arouses the desire to be peacefully united, in the manner determined by Christ, as one flock under one shepherd". The Council's Decree on Ecumenism, referring to the Orthodox Churches, went so far as to declare that "through the celebration of the Eucharist of the Lord in each of these Churches, the Church of God is built up and grows in stature". Truth demands that all this be recognized.
Source: Ut Unum Sint (Vatican.va)