This paper will explore catholicity as a principle for renewing fundamental theology. How can it serve as a single conceptual tool for understanding the nature of a field that consists of diverse methods, various loci, and developing insights? Fundamental theology seems to have come to a standstill. Theologians are either less concerned with method, or they have dispersed their methodological concerns over a variety of other disciplines while focusing on current practices and contexts of faith. Postfoundational and postcolonial critiques have contested the basic assumptions of fundamental theology. In After Method, Hanna Reichel advocates a more playful crossing of different approaches and redirects the attention to marginalized and "misfits". But how to avoid this leading to methodological tribalism in academic networks of the like-minded? In Theology Today, the International Theological Commission expressed its concern over the fragmentation of method and calls for a catholic unity of theology and a multitude of forms with "distinctive family traits". But how to avoid uniformity when setting a single standard undergirding theological principles and criteria? Bob Schreiter proposed a 'new catholicity' as a qualitative principle for a global and missionary theology that does justice to cultural, interreligious and methodological pluralism. Could this 'outsourcing' of theological loci (ad extra) also be used as an instrument for understanding the intrinsic dynamic in and through which theological method can be identified as 'catholic' (ad intra)? And could this new catholicity meet post-Enlightenment objections and renew fundamental theology, attuned to diversity, and accountable for its openness to new sources?