Predestination and prayer

A stock objection to Calvinism is that predestination makes prayer pointless. Ironically, there's a parallel objection based on the providential inutility of foreknowledge. So classical freewill theists are on the hook for an analogous objection.

But back to Calvinism. Let's take a comparison: a movie has plot. But the fact that it's scripted doesn't mean it makes no difference what the actors/characters do. Rather, the plot unfolds in a certain way because of what the actors/characters do, which in turn depends on the script. They follow the script. The plot doesn't play out in spite of what the actors/characters do, but rather, actors/characters have an instrumental role by enacting the script.