29 For this reason, the Council's Decree on Ecumenism also emphasizes the importance of "every effort to eliminate words, judgments, and actions which do not respond to the condition of separated brethren with truth and fairness and so make mutual relations between them more difficult". The Decree approaches the question from the standpoint of the Catholic Church and refers to the criteria which she must apply in relation to other Christians. In all this, however, reciprocity is required. To follow these criteria is a commitment of each of the parties which desire to enter into dialogue and it is a precondition for starting such dialogue. It is necessary to pass from antagonism and conflict to a situation where each party recognizes the other as a partner . When undertaking dialogue, each side must presuppose in the other a desire for reconciliation , for unity in truth . For this to happen, any display of mutual opposition must disappear. Only thus will dialogue help to overcome division and lead us closer to unity.
Source: Ut Unum Sint (Vatican.va)