What is ‘double predestination’? And so you know I’m not asking sarcastically, I am desperately fighting off the urge to make a ‘double secret predestination’ crack...
Double Predestination: God chose whom to save and whom to doom, in the womb. As concerns salvation, there’s no free will, it’s all predetermined, salvation and condemned to hell. The difference between the doomed and saved has nothing to do with them individually, it’s at God’s pleasure.
It’s tied up in the rest of Calvin’s theology.