Their defence: evil comes by God's decree but not his efficiency; the creature fails; the entity of the act is good
They deny, however, that this makes God the author of sin. Evil happens as God has decreed, yet God is not the one who works it: it comes from the creature falling short, under a definite permission of God.
And although what is positive in an evil action is traced to God as its efficient cause, God is not for that reason the cause of evil. The being of an action, however evil, is good, whereas malice formally consists in a certain lack of rectitude.
Latin
XXVIII. Nec tamen inde sequi putant Deum esse peccati autorem: quoniam licet malum Deo decernente fiat, nihilominus non fit Deo efficiente, sed creatura ex certa permissione Dei deficiente. Ac quamvis quod in actione mala positivum est ad Deum ut ad causam efficientem referatur, non tamen propterea Deus mali causa est, quia nempe actionis quantumvis malae entitas est bona, malitia vero formaliter in quadam rectitudinis privatione consistit.