Let me attempt my own explanation of ecumenical reception. First, what is meant by reception? Imagine a major political party that decides on a substantial policy change. Its first task is to persuade its members. This is simple basic reception, where a decision is made by the governing body of an organisation and it must ensure, for the decision to be effective, that it is accepted by its members. A number of factors will come into play and not least amongst these would be the members' understanding of the party's founding principles.
Reception applies within churches too. Presumably, the early church would have perceived reception as simply working out the implications of their faith as the widening membership encountered new challenges. Reception should not be confused with evangelism, which is about telling the good news to new people. Reception is agreeing on what the believers in fact believe.
Ecumenical reception is more complex because members of various denominations are being asked to receive new ideas that do not originate solely from the councils of their own traditions.
William Rusch's in his book Ecumenical Reception offers a variety of definitions of the term. One of them, from Gilles Routhier (page 61), has the advantage of being short and perhaps straightforward.
Reception is a spiritual process by which the decisions proposed by a council are received and assimilated into the life of a local church and become for that church a living expression of the apostolic faith.
The way I see it is this. A council for a major denomination with several thousand local churches make a popular decision. This decision is so popular that every church agrees with it, enthusiastically endorses it and incorporates it into their life. The chances are we will find several thousand interpretations of the decision. Usually, decisions are not so popular, are not successfully explained or passed onto the churches and, if more than one tradition is involved the reality will be even more complex. In the latter case we may find not only that the councils of the 2 or more traditions differ but where more than one local church addresses the change their views might be jointly and severally different too. Fortunately, a wide range of interpretations might be acceptable and be perceived as creative interpretation but even so churches will wish to understand and interpret this variety.
These are merely the problems ecumenical reception seeks to address but I suspect there are some problems with the way it is framed. Return to the Routhier definition and note the movement is all one way from council to local church. There is no real recognition that there might be a conversation not only between the council and local churches but also between local churches.
A decision made by a council might be itself in response to demands from local churches, who find existing regulations no longer meet the needs of their mission. Indeed much ecumenical work begins with local churches, who then ask their councils for changes. But this will not merely start locally, the dialogue has to continue into the later reception period. And of course if it is a dialogue, who can predict where it might lead?
Ecumenical reception implies then that ecumenical conversations are not only between traditions but also within them. Neglect the internal conversations and serious problems are likely to be encountered.
But this is in fact a conversation in three dimensions and I will turn to the third dimension tomorrow.