Schellenberg has an interesting argument that evil is incompatible with the existence of God. The idea is this. God creates in order to make beings that model God's good features. Now each of the goods that God exemplifies is pure: it logically requires neither the existence nor the permission of evil for its existence, e.g., in the way in which courage requires the existence of evil (either the feared evil or an illusion of it, which is itself). The beings that God creates are thus created to instantiate particular goods that are instances of the same types of goods that God's pure goods are supreme instances of, and that model the divine goods. Thus, God may create a limited knower that it might instantiate the good of knowledge, of which God's omniscience is a supreme instance of.
But now since the goods that God exemplifies are pure and supreme, it seems that God can always do better than creating a creature in order to instantiate impure goods like courage. For any good g that God would want to have instantiated is going to fall under the same type T as some divine good G (indeed, I think Schellenberg thinks they wouldn't be goods if they didn't fall under the same type as some divine good). But the divine good G is pure. So it is possible for there to be a being that instantiates a pure good that falls under T. Moreover, since the supreme good in the type T is the pure divine good G, we shouldn't think that the impure goods in T are somehow better than the pure ones—there should be better and better pure goods in T, approaching the divine good G. So God should create one of these better pure goods.
Now, I think there are at least two things wrong here. The first is that even if the supreme good G falling under T is pure, this does not mean that the pure non-divine goods falling under T are better models of G than the impure ones. For it could be that although they better model G in respect of purity, they more poorely model G in respect of some more important feature.
Second, it could well be that all of the non-divine goods falling under T have to be impure. Here is an analogy. God's self-understanding is an instance of self-divinization: seeing oneself as divine. God's self-understanding will, according to Schellenberg, be an instance of some type T of good. The divine instance of T thus has the property of self-divinization. But no non-divine instance of T has the property of self-divinization: a self-divinizing self-understanding can only be a good when it is had by God. What I said about self-divinization could, in principle, hold for purity. It could be that none of the non-divine instances of T have purity.
Here is a non-trivial case. Here is a good feature of God: God is responsible for choosing correctly. This good feature is an instance of some type of good. Presumably the relevant type T to consider is: being responsible for choosing rightly. But now any creature that is responsible for choosing rightly has to be able to choose wrongly (maybe not at this point, but at some point). This is controversial, but since Schellenberg expressly says he accepts the Free Will Defense, he should accept something like this. God, on the other hand, is responsible for choosing rightly without the ability to choose wrongly. How to hold these things together is a difficult question (maybe divine simplicity is relevant; maybe the fact that a deterministic creature would have all its actions externally caused is relevant), but theists who accept the Free Will Defense generally do hold them together. Given this, while a divine instance of T will be pure, necessarily every creaturely instance of T will be impure, and Schellenberg's argument fails. Basically, the Free Will Defense defeats Schellenberg's new argument, even though the argument was designed to get around the Free Will Defense.
The above is right on non-Molinist versions of the Free Will Defense. But the point needs to be modified on the Molinist version of the Free Will Defense. If the Molinist version of the Free Will Defense works (and I think it doesn't, but again Schellenberg seems not to object to it), and if responsibility for choosing rightly requires signficant freedom, then it is possible that every feasible world (world God can create given the conditionals of free will) that contains a creature responsible for choosing rightly also contains a creature that chooses wrongly. If so, then it's possible that God could model responsibility for right choices only in worlds where there happens to be a wrong choice as well.