How did Vatican II change Roman Catholic relations with Eastern Orthodox and Protestant Christians?

The Second Vatican Council (1962–1965) marked a historic shift in the Roman Catholic Church’s approach to other Christian traditions, moving away from a stance of denunciation toward one of fraternal understanding and dialogue.1

Regarding relations with Eastern Orthodox Christians, the council helped improve ties that had been strained since the East-West Schism of 1054. Notably, in 1965, Pope Paul VI and Patriarch Athenagoras I revoked the mutual excommunications that had existed for centuries. Furthermore, the council recognized the validity of the sacraments within Eastern churches, laying the groundwork for ongoing theological dialogue aimed at fostering ecumenism.2

In its relations with Protestant Christians, the council signaled a departure from the church's previous hesitation to engage in the ecumenical movement. By extending the hand of friendship rather than labeling these groups as heretics, the council opened doors for bilateral and multilateral discussions on doctrinal issues, such as the doctrine of justification, which was later addressed in landmark joint declarations. This spirit of openness remains a cornerstone of the church's modern commitment to Christian unity.31