The concept of ‘catholicity’ (from the Greek: kath’holou, according to the whole) is shared by the majority of the world’s Christians, who profess belief in the ‘one, holy, catholic and apostolic church’ (Nicaea).

At a time when ecclesial communities are riven by polarisation, and the secular world seems increasingly divided into incommensurable silos and political echo-chambers, a reappraisal of this central idea of Christianity is not merely desirable but essential. It is increasingly difficult to articulate the ‘common’ or locate the ‘whole’ which frames us: we collapse manifold different kinds of difference into binaries of mutual exclusion or the indistinctness of diversity. A constructive analysis and retrieval of the concept of catholicity may help ameliorate this situation both within the Roman Catholic and other Christian contexts, and more broadly in a variety of not explicitly religious contexts.

For much of its history the concept of catholicity has been understood quantitatively, that is, in terms of geographical, temporal, or numerical extension. In this understanding, catholicity is near-synonymous with ‘universality’ and tends towards uniformity. However, catholicity may also be understood qualitatively: a fullness or unity-in-difference grounded in certain theological qualities or doctrines – including Christological, pneumatological, or creational—all undergirded by the presence of Christ and the pleromatic fullness of God. This understanding is truer to the first appearance of the term in a theological context, in Ignatius of Antioch’s Letter to the Smyrneans, where he locates catholicity in Jesus Christ: ‘wherever Jesus Christ is, there is the Catholic church’.

It is such qualitative understandings of catholicity which this project explores and develops, taking as its starting point the ressourcement theologians of the early and mid-twentieth century. These theologians share a passion for catholicity understood qualitatively, and a heightened sensitivity to the ways in which this ‘whole’ holds together and is constituted by multifarious finite differences. Catholicity, for these theologians, is primarily a quality of God, and only derivatively a quality of the church or creatures.

The ressourcement approach to catholicity remains relevant in our own very different time, both within the Church and beyond. If our investigations generate ways of understanding catholicity theologically which better co-ordinate parts and wholes, the finite and the infinite, such that their integrity and flourishing are enhanced, then these will find wide application in the Church and outside it. Christianity and the secular world need to find middle ways between warring particularisms locked into mutual exclusions, and the flat hegemonic globalisations of uniformity. We need ways of being, thinking, and acting in which the particular and universal or common are mutually upbuilding rather than locked in zero-sum games.

This multi-year international project has begun in 2021 with a series of preparatory seminars based on suggestive texts by ressourcement theologians and others. These meetings are refining the scope of the main project, which will launch in the summer of 2022 with an international seminar in Rome.

This project is led by three chief investigators:

  • Dr Philip McCosker (ACU) – Lead Investigator
  • Prof Stephan van Erp (KU Leuven/ACU)
  • Prof Judith Wolfe (University of St Andrews/ACU)

For further information about this project please email


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