KARL RAHNER, ACUTELY AWARE of the modern philosophical impact on metaphysics, claimed that metaphysical reflection is so fundamental to theology that, "should all philosophers declare the death of metaphysics, he would simply create the necessary philosophical tools within his own theology." (1) Rahner was not alone in his conviction. His contemporary Hans Urs von Balthasar said that, if Christian proclamation and theology made claims of absoluteness on everything that is, then its roots must be in both the historical and metaphysical spheres. (2) "Metaphysics," Walter Kasper writes, "is the name given to the science which enquires not about individual beings or realms of being but about being as such and as a whole. Talk about God presupposes the metaphysical question about being and at the same time keeps this question alive." (3) Balthasar viewed philosophical inquiry as not only pertinent to the task of theology but as integral to Christian life: "The Christian is the person who by virtue of his faith is compelled to philosophize," (4) that is, who retains an openness to the meaning of the whole in a way that serves the humanness of humanity and nonhuman creation. What these theologians agree on is that theology cannot be divorced from metaphysics, even though the postmodern turn has tried to bury metaphysics in the crypt of modernity.
In light of the modern separation between theology and metaphysics, Rahner's publication of The Trinity in 1967 sparked a new interest in the renewal of trinitarian theology. It is here that Rahner put forth his famous axiom: "The 'economic' Trinity is the 'immanent' Trinity and the 'immanent' Trinity is the 'economic' Trinity," (5) to try to restore a Christian understanding of God to the practice of Christian life. Although this axiom has been subject to criticism for, among others things, failing properly to distinguish God and world, (6) Rahner's axiom provided a theological-metaphysical ground to salvation history by highlighting the mystery of God in creation.
Catherine LaCugna, deeply influenced by Rahner's trinitarian theology, sought to establish an integral relationship between ontology and soteriology through a renewed understanding of the Trinity. Like Rahner, LaCugna aimed to retrieve a credible trinitarian God for Christian life, not only by grounding salvation history in its source but by identifying the relationship between the being of God (ontology) and the action of God (soteriology) leading to a shared life between God and creature. Both Rahner and LaCugna were keenly interested in the authenticity of Christian life and viewed history as the revelation of trinitarian life. Salvation history, they claimed, is metaphysical by nature.
In her description of Rahner's trinitarian theology, LaCugna wrote that "his theology as a whole is a profound meditation on the essential unity of 'theology' and economy, premised on the idea that God is by nature self-communicating." (7) LaCugna claimed that "Rahner's theology of self-communication appears to have roots in Bonaventure's vision of the self-diffusive God." (8) While a critical study has yet to be made of Bonaventure's influence on Rahner, there is indeed a compatibility of thought. Bonaventure's trinitarian theology not only anticipated Rahner's grundaxiom, but Bonaventure developed a theological metaphysics of Christ the center that integrates the immanent and economic Trinity in such a way that Incarnation discloses the essential nature of God as love. Bonaventure's metaphysics is based on a theology of the divine Word by which the two mysteries of Trinity and Christ are intrinsically connected. Christology is a function of theology, and theology has its meaning in Christology. The self-revelation of the Trinity in history is the expression of the divine Word in whom God "speaks" Godself in all things. Creation bears a congruent relationship to the Word of God so that Christ is truly the center and goal of creation and hence its metaphysical center. …