One particularly notorious determinist and I are discussing our different views on God's relation to the events in creation. He thinks that God has made any and every even that happens necessary by divine decree. I hold to libertarianism and think that God created free creatures whose actions are causally distinct from God in some circumstances.
I claim his view seems to implicate God in all sin. He asserts that I don't escape this problem because since I believe that God foreknows all things, He foreknew that the only way sin would happen would be to create free creatures, and that implicates God in their sin. As I argued in my response to James Swan (found here) this is not the case. It is logically inappropriate to transfer the responsibility for the sins of independent creatures to God simply because He foreknows them.
Consider this example that I used in response to this: If no one invented the airplane, then 9/11 wouldn't have occurred. Hence: 9/11 causally depends on the invention of the airplane. Therefore Wilbur and Orville Wright caused 9/11.
Or consider this example: The inventor of the automobile probably foresaw the potential tragedies that could come about from smashing a couple tons of steel into someone, but he obviously thought that the greater good that would come from having such a convenient form of transportation was worth it. He likewise can't be blamed for the negative future consequences that occurred because of the automobile's invention, even though he knew they most likely would occur.
This is where recognizing the difference between necessary and sufficient conditions come in. The creation of free creatures is only a necessary condition for evil. Those free creatures did not have to sin, but in order for them to sin they would have to be free. On the determinist end, however, God's decrees become the sufficient condition for sin. All that is needed for necessitated creatures to sin is the simple decree made by the determiner. The determiner is therefore the responsible party, since they are the one who has made all these events necessary, even sin.