First absurdity: God would be the author of concupiscence, which John says is not of the Father; Bellarmine's rust analogy fails
Indeed, unless we hold this, the gravest absurdities follow. First, it will follow that God himself could be the author of the concupiscence by which the flesh fights against the spirit, since on this hypothesis he could have created man with it. Yet the Roman teachers grant that this concupiscence, even after original sin has been forgiven, has the character of a vice and of a moral evil that God finds displeasing and hateful, and John denies that it comes from the Father.
Bellarmine's reply does not remove the force of this argument. He says that concupiscence would have arisen from matter apart from God's intention, as rust arises on a sword, and the smith is not therefore its author. But the smith did not make the iron from which the rust comes, whereas God did create the matter of our bodies. And even so, rust cannot be on a sword fresh from the smith's hands unless the smith is at fault.
Latin
XLIX. Et certe nisi ita statuamus, gravissima sequentur absurda. Primo enim inde sequetur concupiscentiam illam, per quam caro pugnat adversus spiritum, & quam Scholae Romanae Doctores, etiam post remissum peccatum Originale, concedunt habere rationem vitii, & mali cujusdam moralis, quod Deo displicens & odiosum est, quamque Joannes negat esse a Patre, sequetur, inquam, inde concupiscentiam illam potuisse habere Deum ipsum authorem; qui scilicet, ex hac hypothesi, hominem cum illa creare potuerit. Nec vim argumenti tollit quod Bellarminus Respondet, concupiscentiam istam ex materia fuisse emersuram, praeter Dei intentionem: Ut rubiginem ex gladio, cujus propterea faber ferrarius author non est. Nam faber ferrarius non fecit ferri materiam unde rubigo exoritur, sicut Deus corporis nostri materiam creavit. Et tamen, citra fabri culpam, non potest inesse rubigo gladio ex manibus illius prodeunti.