I have been working on my next paper on Christology. Calvin's doctrine of penal substitution is central to his Christology. This has got me thinking. Does it implicitly deny the Trinity (at least an Orthodox version like Aquinas's)? Consider the following argument. It seems sound to me: 1. The only distinctions between persons in the Trinity is the way they relate to each other. 2. Calvin’s doctrine of penal substitution affirms a debt payment made from Son to Father. 3. Debt payment is a financial metaphor that necessarily depends on the concept of accounts or stores of a commodity that can be used for payment. 4. For the payment to be real (i.e., not fictive) the Son and Father must have separate accounts. 5. Conclusion: Points 1 and 4 are in contradiction to ea...