36 Dialogue is also a natural instrument for comparing differing points of view and, above all, for examining those disagreements which hinder full communion between Christians. The Decree on Ecumenism dwells in the first place on a description of the attitudes under which doctrinal discussions should take place: "Catholic theologians engaged in ecumenical dialogue, while standing fast by the teaching of the Church and searching together with separated brothers and sisters into the divine mysteries, should act with love for truth, with charity, and with humility". Love for the truth is the deepest dimension of any authentic quest for full communion between Christians. Without this love it would be impossible to face the objective theological, cultural, psychological and social difficulties which appear when disagreements are examined. This dimension, which is interior and personal, must be inseparably accompanied by a spirit of charity and humility. There must be charity towards one's partner in dialogue, and humility with regard to the truth which comes to light and which might require a review of assertions and attitudes. With regard to the study of areas of disagreement, the Council requires that the whole body of doctrine be clearly presented. At the same time, it asks that the manner and method of expounding the Catholic faith should not be a hindrance to dialogue with our brothers and sisters. Certainly it is possible to profess one's faith and to explain its teaching in a way that is correct, fair and understandable, and which at the same time takes into account both the way of thinking and the actual historical experiences of the other party. Full communion of course will have to come about through the acceptance of the whole truth into which the Holy Spirit guides Christ's disciples. Hence all forms of reductionism or facile "agreement" must be absolutely avoided. Serious questions must be resolved, for if not, they will reappear at another time, either in the same terms or in a different guise.
Source: Ut Unum Sint (Vatican.va)