in spite of my silly grin, unrighteousness is a real word:

unrighteous adj.
1. Not righteous; evil; wicked; sinful; as, an unrighteous man.
2. Contrary to law and equity; unjust; as, an unrighteous decree or sentence.
un·righteous·ness n.

...certainly to be preferred over wrongeousness (an obvious nonce word :).