What is the literary device in which situations are placed in opposition, (i.e., the opposite of literary parallelism)?
e.g., The LORD's curse is on the house of the wicked, but he blesses the home of the righteous.
There are a couple of possible correct answers to your question.
1. Juxtaposition is a literary technique which describes objects, characters, ideas, etc., being placed next to each other to show similarities and differences. Most often, the two elements placed next to one another are opposites.
2. Antithesis is the use of parallel structure to demonstrate contrasting ideas. A good example is from Brutus's funeral speech in Julius Caesar when he states, "Not that I loved Caesar less but that I loved Rome more."
3. Chiasmus does not necessarily involve opposing ideas, but its structure follows an ABBA format instead of parallelism's ABAB style. For example, JFK's Inaugural Address includes several famous ones, such as "Let us never negotiate out of fear, but let us never fear to negotiate."
The example you offered in your question is an antithesis.