For many people, it can seem as if ecumenism—the work of bringing together divided Christians—is an optional extra. It doesn’t seem to attract as much attention, for instance, as the Church’s care for the poor or the unborn. We may also feel a bit reluctant to delve into this topic too deeply, for fear that we might end up losing sight of our own heritage as Catholics. Or perhaps the topic seems so complicated that we don’t know how to think about it.