Polhill is a helpful guide in that he unites soteriology with Christology and theology proper. His use of categories is more compatible with the broader Christian tradition, and for that reason, we should feel an imperative to re-read many more of the other older divines:
The sufferings of Christ respect both attributes; they satisfied the law, and founded the gospel. Justice had a full compensation, and mercy sprung up in promises of grace and life…
There was in Christ’s sufferings a conjunction of satisfaction and merit: justice was compensated, and grace impetrated. Indeed the Socinians, blind with their own corrupt reason, cannot see how these two should stand together; satisfaction being the payment of a just debt, and merit the doing of an undue work. To which I answer: it is true, that when one pays a finite sum for his own debt, there is not, there cannot be a merit in it; but when Jesus Christ paid down sufferings of an infinite value for us, there cannot but be an immense merit in them. Infinity is an ocean, and may run over in effects as far as it pleases; those sufferings had a kind of infinity in them, enough to pay divine justice, and over and above by a redundance of merit to purchase all grace for us.
~ A View of Some Divine Truths pg. 5