The key question at issue is whether (S2) is true or false:

(S2) But God would neither perpetrate nor permit grand deception regarding the Incarnation and Resurrection.

I have raised two objections against one reason that Cavin and Colombetti give for their conclusion that “(S2) is patently false”. One reason they gave was a passage from the gospel of Mark which they think shows that the author of Mark, and probably Jesus too, had a concept of God which was such that God could (and would) permit a “grand deception” in which many people would be led to believe in or follow false prophets or false messiahs on the basis of “signs and wonders” performed by those prophets/messiahs.

My first objection was simply that the author of Mark may have made a philosophical error in failing to realize that God, who is by definition a perfectly morally good person, could not possibly permit such a “grand deception”.

My second objection was that we should interpret this passage, which is allegedly a quotation from Jesus, in terms of O.T. teachings about false prophets and how to determine whether an alleged prophet is a true prophet or a false prophet.

By placing the passage from Mark in that context, we see that the passage can be reasonably interpreted as being compatible with (S2), because it appears that God could be morally justified in permitting many people to be “deceived” by false prophets or false messiahs who perform “signs and wonders” so long as those people are morally culpable for their own deception in view of their ignoring O.T. teachings (presumably guidance from God) about how to determine whether a prophet was a true prophet or a false prophet.

I suggested that from the point of view of the author of Mark, and probably also Jesus, such deception, though widespread, might not count as a “grand deception” precisely because God would be morally justified in allowing this kind of widespread deception to occur.

Now, there is no need to get into a debate over the meaning of the term “grand deception” (at this point). Suppose that Cavin and Colombetti enhance their argument by providing a clear definition or analysis of the key term “grand deception”. And suppose that under the proposed definition, the kind of case that I have put forward here fits under that definition. In that case, I would accept their proposed definition, but revise my objection to be making an important distinction between different sorts of cases of “grand deception”. I would argue that there are some cases of “grand deception” that God cannot allow, and other cases of “grand deception” that God appears to be morally justified to allow, from the point of view of the author of Mark.

Cavin and Colombetti give a second reason in support of the conclusion that “(S2) is patently false”, and they claim that this reason “establishes…conclusively” that (S2) is false (SOR, p.32). But it seems to me that the argument they give is based on an unstated assumption, and that the unstated assumption is itself “patently false”. So, I will argue that their second argument is unsound.

They point to widespread disagreement about the alleged incarnation of God in Jesus and the alleged resurrection of Jesus:

There is an incontestable item of our background evidence overlooked by Swinburne that shows that his premise that God would neither perpetuate nor permit others to perpetuate a grand deception regarding the Incarnation and Resurrection is false. For it is an undeniable fact that massive religious deception exists in the world regarding, specifically, the Incarnation and the Resurrection. There are, currently, some 2.1 billion Christians, 1.5 billion Jews and Muslims, and 1.1 billion atheists, agnostics, and secularists living today. And, while Christians hold tenaciously to the Incarnation and Resurrection as central tenets of their faith, Jews and Muslims with equal vehemence deny these, as do atheists, agnostics, and secularists.(SOR, p.32)

On the basis of the fact of widespread disagreement about the Incarnation and the Resurrection, Cavin and Colombetti infer that “grand deception” already exists concerning these beliefs:

Yet, the opposing beliefs of each of these groups regarding the Incarnation and Resurrection are either true or false. And, thus, accordingly, it is either the 2.1 billion Christians who are the ones who have the truth or it is the 1.5 billion Jews and Muslims and 1.1 billion atheists, agnostics, and secularists who do. But, either way, the adherents of at least one of these groups are deceived and hold their false beliefs on the basis of deceptive reasoning. In some cases this deception is intentional, although in most it is probably unwitting and self-inflicted. And the problem for Swinburne is that the extent of this deception, unwitting or otherwise, is global–indeed, truly grand.(SOR, p.32)

The reasoning above can be summarized as follows:

1. The adherents of at least one of these groups (each containing over a billion people) hold false beliefs about the Incarnation and Resurrection.

Thus:

2. The adherents of at least one of these groups (each containing over a billion people) are deceived concerning the Incarnation and Resurrection and hold false beliefs about the Incarnation and Resurrection on the basis of deceptive reasons.

As it stands the above inference is a non sequitur. In order to properly infer (2) from (1), we need to make an unstated assumption explicit:

(D) IF a person P believes a proposition X, and X is false, THEN

P has been deceived concerning X and P believes X on the basis of a deceptive reason.

As far as I can tell, this is an assumption being made by Cavin and Colombetti in order to correctly infer (2) from the true factual premise (1). But (D) is “patently false”, so the argument for (2) is unsound.

It is not difficult to come up with a counterexample which disproves (D). Suppose that on Tuesday morning I watch a weather forecast on T.V. and the person giving the weather predicts that it very likely to rain in the early afternoon. Based on this forecast, I form the belief that it will rain sometime in the afternoon. But on this particular day, the forecast was wrong, and it does not in fact rain. Thus, the belief I formed, namely that it would rain in the afternoon, is false. Based on (D), we can conclude that I had been “deceived concerning” whether it would rain in the afternoon, and that my belief that it would rain that afternoon was formed “on the basis of a deceptive reason”.

But this is clearly NOT the case. The weather person did NOT deceive me either wittingly or unwittingly. Nor did I deceive myself. Furthermore, my belief that it would rain that afternoon was NOT formed on the basis of a deceptive reason. I had a perfectly good reason for forming the belief that it would rain that afternoon. My belief was a justified belief, a rational belief, and the reason was in no way a deceptive reason. It is simply the case that when one reasons to probable conclusions, the conclusion will sometimes be wrong. That is the whole idea of probable reasoning; it does not produce absolutely certain conclusions.

The unstated assumption (D) is clearly false, and so the argument based on this assumption is unsound, and therefore the argument does NOT “establish…conclusively” that (S2) is false.