(This is the second post in my series on psychology & religion. See here for the first.)
It's fashionable these days to think that neuroscience, particularly certain kinds of brain imaging studies, undermines religious beliefs in so far as those beliefs are based on claims to genuine religious experience. On closer examination, however, this kind of neuroscientific debunking argument is unsuccessful. To argue for this claim, we'll return to Gregory Peterson's article, which has a very helpful discussion of the argument in question.
The basic thought behind the argument is this: neuroscience, by finding neural correlates that are sufficient for religious experience , undermines the claim that such experience is genuine, and (to the extent that religious experience serves as justification for religious belief) undermines religious belief. But there are two ways neuroscience can threaten the validity of religious experience: by threatening its content or its causal origins.
Typically, Peterson writes, genuine religious experiences are regarded as having a particular kind of content as well as a special sort of causal history. I don't think either of these are necessary conditions on genuine religious experience. Against the first, consider Augustine's 'tolle lege,' which is not any special kind of content as such; and against the second, it should be noted that it's consistent (on at least some ways of construing the interaction of God with the natural realm) with an experience being genuinely religious that it has a purely natural causal history.
Those concerns aside, are neural correlates a threat to the content and causal origins of religious experience? Peterson thinks, and with this I tend to agree, that neural correlates tell us very little about the content of religious experience, so there is not a threat in that regard. As for the causal origins of religious experience, there may be some threat from neural correlates, but a rather limited one. As Peterson writes: the religious believer would have to admit that “the human mind is primed for… religious experiences but that it can be manipulated to produce false positives.”
It's important to notice that this is a very minor threat, indeed perhaps more minor than Peterson suggests. Consider an analogy to color experience. Suppose neuroscientists could artificially induce the experience of red. This would tell us little about the verdicality of non-artificially induced red experiences. At most it tells us that beliefs formed on the basis of such experiences are fallible, but doesn’t undermine our confidence in those beliefs. Note that it doesn't show that outside the laboratory context our color beliefs have the wrong kind of causes. This analogy strongly suggests that the ability to induce religious experience in a laboratory is no threat to religious experience in the field, as it were. Nor should a similar result pertaining to religious experience undermine our confidence in religious beliefs. It's presumably widely agreed, and not at all problematic, to point out that our religious beliefs are fallible and can be caused by the wrong sorts of things, and that seems to be the most that the neural correlate argument establishes. The argument does not show that religious experiences out in the field do not have the kinds of causes that religious believers take them to have.
It appears, then, that neural correlates pose a very limited threat to the causal origins of religious experience, and no threat at all to the content of religious experience. The neuroscientific argument against religious beliefs has been found wanting.
 Psychologists disagree about whether such correlates have already been found. For our purposes we can stipulate that they have.