So we’ve established that reconciliation between churches is possible if 1) there was a misunderstanding or 2) there were different traditions with a church. The third possibility that lies before us is change.
Change is famously alarming to churches and church people; but it’s a constant of church life and not good or bad in itself. Some change is good, the work of the Holy Spirit who “will guide you into all truth,” as Jesus said in John 16:13. Some change is bad, turning to a “different gospel” (Galatians 1:6). It’s the content of the change that requires assessment, not the fact of change.
An example of a change leading to church reconciliation can be found in the Leuenberg Agreement (1973), which laid out the basic parameters for fellowship between Lutheran and Reformed churches in Europe. One of the three major points it addressed was predestination, which used to be a dividing point between Lutherans and Reformed.
In §25, the Leuenberg Agreement says: “The witness of the Scriptures to Christ forbids us to suppose that God has uttered an eternal decree for the final condemnation of specific individuals or of a particular people.”
This is, in fact, exactly the opposite of what Reformed churches following Calvin taught in the 16th century. The Reformed churches of today have changed: they no longer believe in “double predestination,” and thus there is no longer any disagreement with the Lutherans.
It is interesting to note that this change of opinion was not the result of a “Lutheran” victory, but the influence of the Reformed theologian Karl Barth in his own church. And it wasn’t a matter of “giving up” something precious to an outsider but a deepening and maturing in theological understanding.
So if there’s been a cleared-up misunderstanding, or a decisive choice for one particular tradition out of several competitors, or a change, it’s possible for previously separated churches to say:
“[T]he doctrinal condemnations expressed in the confessional documents no longer apply to the contemporary doctrinal position of the assenting churches” (Leuenberg Agreement §32.b); or
“In light of this consensus, the corresponding doctrinal condemnations of the sixteenth century do not apply to today’s partner” (The Joint Declaration on the Doctrine of Justification §2.13).