Some will claim that this quote has to be read in its proper context. I have read it in its proper context and Calvin means by it exactly what it says. In the following sections he goes to great lengths to defend it against the “blasphemous” and “foolish” opposition of others.
So, it seems to me where the inquiry has to go is toward identifying how (and if?) Calvin’s double predestination differs from what Islam says about Allah.
If we say, “How can God make people for everlasting torment and not be evil?” my recollection is that the appeal will be made to the inscrutable sovereignty of God. IOW Calvin preserves God’s at the expense of knowing how he’s good.
And that’s what makes theology interesting.