38 In dialogue, one inevitably comes up against the problem of the different formulations whereby doctrine is expressed in the various Churches and Ecclesial Communities. This has more than one consequence for the work of ecumenism. In the first place, with regard to doctrinal formulations which differ from those normally in use in the community to which one belongs, it is certainly right to determine whether the words involved say the same thing. This has been ascertained in the case for example of the recent common declarations signed by my Predecessors or by myself with the Patriarchs of Churches with which for centuries there have been disputes about Christology. As far as the formulation of revealed truths is concerned, the Declaration Mysterium Ecclesiae states: "Even though the truths which the Church intends to teach through her dogmatic formulas are distinct from the changeable conceptions of a given epoch and can be expressed without them, nevertheless it can sometimes happen that these truths may be enunciated by the Sacred Magisterium in terms that bear traces of such conceptions. In view of this, it must be stated that the dogmatic formulas of the Church's Magisterium were from the very beginning suitable for communicating revealed truth, and that as they are they remain for ever suitable for communicating this truth to those who interpret them correctly". In this regard, ecumenical dialogue, which prompts the parties involved to question each other, to understand each other and to explain their positions to each other, makes surprising discoveries possible. Intolerant polemics and controversies have made incompatible assertions out of what was really the result of two different ways of looking at the same reality. Nowadays we need to find the formula which, by capturing the reality in its entirety, will enable us to move beyond partial readings and eliminate false interpretations. One of the advantages of ecumenism is that it helps Christian Communities to discover the unfathomable riches of the truth. Here too, everything that the Spirit brings about in "others" can serve for the building up of all Communities and in a certain sense instruct them in the mystery of Christ. Authentic ecumenism is a gift at the service of truth.
Source: Ut Unum Sint (Vatican.va)