Reading theology from the previous century has the power to trick you into thinking that reunion between the divided communions was, and remains, a live possibility. As late as 1999, when Robert Jenson published the second volume of his systematic theology, the bulk of which is a fulsome ecclesiology in close conversation with both Vatican II and the most recent ecumenical dialogues, you would be forgiven for getting the impression that reunion—between Rome and Wittenburg, between Rome and Canterbury, even between Rome and Constantinople—was conceivable within our lifetime, even right over the horizon.