 As mentioned above, acts of sin relate closely to those versions of the problem of evil that focus on moral evils, where one tries to explain free creatures doing what is wrong. It is common in these discussions to differentiate a defense from a theodicy. Alvin Plantinga describes a theodicy as “the attempt to specify God’s reason for permitting evil”, while a defense is the attempt to specify not what God’s reason is but what it “might possibly be” (Plantinga 1977: 27f; see also van Inwagen 2006). Versions of free will theodicy argue that the existence of free will is the good that justifies God’s permitting evil, while free will defenses argue that the existence of free will might be such a reason. Both free will theodicies and defenses typically presuppose libertarian understandings of free will, and thus the possibility of moral evil, although they need not (see, for instance, Almeida 2016 and Turner 2013). Given the focus here on sin, one particular response to the problem of moral evil is worth extended attention: a response known as “O Felix Culpa”, according to which God not only allows but even desires evil insofar as it furthers his plans.