Stenger was an early supporter of the Internet Infidels; we occasionally exchanged emails. Trained as a physicist, Stenger was also interested in the philosophy of religion. Many of his writings were at the intersection of physics (or, more broadly, science) and religion.
As I reflect upon my numerous interactions with him about responding to theistic arguments, it seems like we more often disagreed than we agreed. I, for one, was very critical of his debates with William Lane Craig. (See here.) In no particular order, here were some of our disagreements.
1. Big Bang cosmology and whether the universe came from “nothing.” Like other atheist scientists (such as Isaac Asimov, Peter Atkins, and Lawrence Krauss), Stenger defended the idea that the universe could (did?) come from “nothing.” For example, commenting on Krauss’s book, Stenger wrote:
The “nothing” that Krauss mainly talks about throughout the book is, in fact, precisely definable. It should perhaps be better termed as a “void,” which is what you get when you apply quantum theory to space-time itself. It’s about as nothing as nothing can be. This void can be described mathematically. It has an explicit wave function. This void is the quantum gravity equivalent of the quantum vacuum in quantum field theory.
As is/was the case with Asimov, Atkins, and Krauss, however, it turns out that what Stenger meant by “nothing” is actually something. By definition, it is philosophical nonsense to talk about absolute nothing ‘having’ anything (such as having energy, a wave function, etc.), as if “nothing” were an object capable of having properties (such as mass, location, etc.). In this sense, one might say that Stenger and company are/were literally talking past their theistic critics–they are/were both using the same word (“nothing”) but in totally different ways. Or, to put the point another way, what we have here is the “illusion of communication.”
2. The “Multiverse Objection” to Fine-Tuning Arguments. Is the multiverse hypothesis a good objection to cosmic fine-tuning arguments for God’s existence? Stenger argued “yes” whereas I argued “no.” (See Stenger’s books for his argument; see here for mine.)
3. The “Lack of Evidence Argument” (LEA) for God’s nonexistence. Stenger thought that this was a good argument, but I argued it was not, even if we assume that there is absolutely zero evidence for God’s existence. (See here.) Consider recent attempts to scientifically test whether prayer actually works. As Stenger correctly noted, recent scientific studies have failed to confirm the efficacy of prayer. Stenger argued that this result, by itself, is an example of the lack of evidence for God’s existence and so is evidence against God’s existence. Two points.
First, I agree that the lack of scientific confirmation of answered prayers is some evidence against God’s existence, but I don’t think it’s the “killer” argument Stenger (and some other atheists) make it out to be. (Why? See here.)
Second, Stenger understated the evidence about prayer and so made his case weaker as a result. While Stenger appealed to what we might call “negative” evidence (the lack of evidence for answered prayer), he ignored the “positive” evidence (evidence we do have which is less surprising on naturalism than on theism). This positive evidence includes: (a) the fact so much in medical science is intelligible without any appeal to answered prayers or other forms of supernatural agency; and (b) the history of medicine contains no examples of answered prayers replacing a naturalistic explanation for healing. (a) and (b) are more probable on the assumption that naturalism is true than on the assumption that theism is true and so are evidence for the former and against the latter.
In spite of these (and other disagreements), however, I greatly respected him and am sad that he is gone. He will be missed.