The alternative of hypothetical universalism, according to which Christ's work is sufficient for all but efficient only for the elect, was alive and well in early Reformed thought. Moreover - and importantly for our purposes - this view was not regarded as an aberration but as a legitimate position that could be taken within the confessional bounds of Reformed thought. But that means that the Five Points aren't the non-negotiable conceptual core of Calvinism after all.

I recommend Doug Sweeney's recent book [Jonathan] Edwards the Exegete (Oxford University Press, 2015), which is a terrific treatment of the way in which Edwards was steeped in the Bible, so that it shaped the whole of his thinking.

Now, don't get me wrong: I'm not rubbishing penal substitution. But there are other options that have been advocated by Reformed thinkers of the past.

[Jonathan] Edwards definitely shows up in the book [Saving Calvinism]. He appears as one of the interlocutors in the chapter on free will, the other being the Southern Presbyterian theologian John Girardeau.

The expansion I have in mind isn't the same as distortion. Of course, there are those who say their views represent Reformed thought, but what they end up with is a caricature of what Reformed thinking is really about. I hope I am not one of those people, but readers [of the Saving Calvinism] will have to make up their own minds on that score!

We may think that our tradition is exactly the same as it has always been, but that is an illusion.

In the chapter on the nature of the atonement [in the book saving Calvinism] I argue that it is a mistake to think that penal substitution is the only option on the doctrine of atonement.