That might also just mean that they are inconsistent (or that they reject such a concept of metaphysics).
A quote from the Solid Declaration of the
Formula of Concord,
article VII, paragraph 37:
Even as many eminent ancient teachers, Justin, Cyprian, Augustine, Leo, Gelasius, Chrysostom and others, use this simile concerning the words of Christ’s testament: This is My body, that just as in Christ two distinct, unchanged natures are inseparably united, so in the Holy Supper the two substances, the natural bread and the true natural body of Christ, are present together here upon earth in the appointed administration of the Sacrament.
The words translated ‘natures’ are
substantiae in Latin and
zwei Wesen in German.
This is either consubstantiation (which states nothing more than the idea that in the sacrament of the Altar, the substance of the body and blood of Christ is present alongside the substance of the bread and wine) or impanation. It cannot be impanation, or else we would have received through the Confessions the belief that Christ is ‘true God, true man, true bread, and true wine.’
I see no difference between ‘consubstantiation’ and ‘sacramental union’ (as presented in the above paragraph). Where is this supposed difference? If the answer is that we shouldn’t use philosophical explanations and rather ‘embrace the mystery,’ I answer that in using
substantia and
Wesen, the confession has already used philosophy. And moreover, that philosophy isn’t bad in and of itself. The doctrine of the Incarnation, as we have received it from Nicea and Constantinople, and which is attested in
Confessio Augustana I-III, depends itself on a philosophic explanation – i.e. that Christ is ‘of the same essence as the Father’ or ‘consubstantial with the Father.’ This, of course, doesn’t diminish the mystery of the Incarnation, and neither does a philosophical treatment of the sacraments.