Canlis notes two revolutionary innovations in Calvin’s doctrine of the Spirit: “First, he has shifted the primary bond between the human Jesus and the Father from divine substance to the divine person of the Spirit.” That enables Calvin to rescue Chalcedon from confusion: “rather than two naked natures coexisting without mingling, Calvin treats the whole person of Christ who, by the Spirit, is kept truly human and truly divine. The Holy Spirit represents a new way of being in relationship – the joining of two unlikes in a relationship of particularity and yet union.”
Second, Calvin is enabled to shift the bond between God and humanity from a more Platonic view (based on an ontological similarity between divine and human) to the person of the Holy Spirit. Once again, an abstract ‘similarity’ or ‘point of contact’ is subverted for a person, anchoring human participation only in God himself, beginning with the self-gift of God to us in the person of the Spirit.” Canlis notes elsewhere that for Calvin natural theology is part of his pneumatology.
All this suggests a broader point: When the Spirit is set aside, all sorts of other principles and constructs take His place. What binds the Son and Father is not the Spirit, but a fourth something, the essence, in the Trinity. What binds God and creation is not the Spirit, but some analogia entis or, worse, a continuum of being. What binds the Eucharistic community to its head is not the Spirit, but a substantial transformation of bread and wine. Without the Spirit, natural theologies and natural law intervene.
When the Spirit is set aside or marginalized, theology gets ontologized, depersonalized, alienated from its Trinitarian substance. What we need is a pneumatological ontology.