The smarter Anchorites will not open the debate on predestination. Reformed live to debate that topic, and many Anchorites probably realize that they themselves are logical open theists on that point. No, they will open the move on effectual calling, stating that it involves a coercion of the will, which means–if there is a 1:1 correspondence between our humanity and Christ’s–that Christ didn’t have a fully human will.
They are correct that the key point is effectual calling. Effectual calling, as Kevin Vanhoozer aptly summarizes, illustrates the problem of a causal nexus between God and the world. Every theology must own up to this. Ever since Descartes’ insights about the mind-body dualism, philosophers and theologians had to face the question: that there is a distinction between Creator and creature (or mind and body for that matter), how can one affect/effect the other?
For all of the problems and difficulties with the Reformed answer, it can at least answer this question. I doubt Anchorites can.