As a key contributor to the current discussion of the Catholic theology of religions, Gavin D'Costa's writings represent a consistent attempt to utilize the resources of the doctrine of the Trinity to address a number of issues regarding the theological significance and function of religions in the salvific plan of God. The aim of this thesis is to examine critically his Trinitarian theology of religions through the lens of a main proponent of patristic theology, Basil of Caesarea, and through a historical-systematic study, address the question of whether his underlying Trinitarianism is consonant with classical Trinitarian theology. After a discussion of Vatican II and post-Conciliar sources, the main contours of D'Costa's theology are highlighted through an interpretive grid of particularity/universality (Christology/Pneumatology) with a second-order universality/particularity. Despite his distancing from the three-fold typology of exclusivism-inclusivism-pluralism, we analyzed that much of his theology continues to fall within the category of traditional inclusivism, particularly since his recent proposal of the limbo of the Fathers contained serious difficulties pertaining to his intention to maintain a singular OT Judaism-Christianity relationship. Next, we examined the main features of Basilian Trinitarianism, and proposed that three major themes are of relevance for a comparative analysis with D'Costa's theology, namely, (1) the doctrines of divine simplicity and inseparable operations, (2) the enlightening work of the Spirit, and (3) the theology of baptism and theosis. Throughout the discussion, in recognition that Basil's thought is part of the patristic theological matrix of his time, we will also reference the writings of other Church Fathers, including Gregory of Nyssa, Gregory of Nazianzus, and Augustine. We concluded that while in Basil's theology, economy, relationality and ethics are intricately woven into each other, D'Costa's system, despite its significant merits, was at risk of disaffiliating the connections between the three.