The Christian platonist must insist that abstracta are they way they are because they, not God, are the very essence of uncreatable reality, and that they delimit all possible realities, even God’s nature. Hence, abstracta are explanatorily (if not causally) prior to God’s nature.
But the nature of certain abstracta clearly seem explanatorily posterior God’s nature. For example, necessarily true propositions the truths of which are determined by God’s nature—e.g., necessarily true moral propositions, such as it is wrong to torture babies for fun. The orthodox theist can explain why this is a necessarily true proposition—because moral goodness, as God’s very nature, delimits what necessary moral truths there are, it is wrong to torture babies for fun being one of them.
But here the Christian Platonist confronts a dilemma: he must either deny that the nature of all abstrcta is explanatorily prior to God’s nature, or he must reaffirm this but deny that the abstracta typically seen as explanatorily posterior God’s nature, such as necessarily true moral propositions, are so.
The former move seems very arbitrary and ad hoc. It has us believe that only certain abstracta are the way they are independently of God. But what calls for the difference? It is hard to see what, if anything. If one says “God’s nature,” then incoherence looms, for really this amounts to saying “God’s nature determines which abstracta are explanatorily posterior his nature.” Not only is this obviously circular, it faces the further question, “what about God’s nature determines which abstrcta are explanatorily posterior his nature?” Either way the first horn of this dilemma does not seem palatable.
The second horn states that all abstracta, even necessarily true moral propositions, are the way they are just because. They are the very essence of uncreatable reality, and they delimit all possible realities, including God’s nature as it were. But this horn immediately puts the Euthyphro dilemma back on the table, for it can no longer be said that certain things are good because God’s nature is such, but, quite literally, God’s nature is such because certain things are good. This would also remove any potential for the moral argument for God’s existence, as the explanation of any moral truth would not be in terms of God’s nature, but in terms of a general reality apart from God.
Because it is not a brute fact that God’s nature is good, the question of why God’s nature is good for the Christian Platonist becomes very difficult to answer. It just seems convenient that he is good. Moreover, strictly speaking, God’s nature cannot be good, for if it were, then no further account of goodness is needed. If the Christian Platonist maintains that God’s nature is good, then the further account of goodness in terms of abstracta is superfluous. But if the Christian Platonist maintains that goodness is not strictly God’s nature, then God’s goodness becomes a contingent matter.
Thus, like the attribute of aseity, goodness as a divine attribute also seems attenuated on a Christian platonist view. The second horn of the dilemma also seems unpalatable.