Since the schism of 1054, the Catholic and Orthodox churches have shared a long and often turbulent history. Since then, there has been a need for ecumenical action. Although there have been attempts at unification throughout history, ecumenism was viewed with caution until the 20th century. Today, the need for ecumenism is recognised, that is, it is obvious that Christians must work on mutual dialogue and unity in diversity. Even today, when there is an ecumenical movement, many look with suspicion at individuals and organisations that are actively engaged in this task. The Catholic and Orthodox Churches have many things in common, but also many differences, which are often the source of conflict and mistrust. Over time, it has been possible to reach agreement on the validity of the sacraments so that the faithful are not deprived of the need for spiritual goods in extraordinary and difficult situations. One of the most significant events in the history of the Catholic and Orthodox Churches, dating back to 1965, was the abolition of mutual excommunications dating back to 1054. A concrete example of dialogue between ordinary believers is mixed marriages. Although they are a difficult way of life and are rarely recommended, they are an example of dialogue and living in peace.