Infidelis Maximus and A Whore in the Temple of Reason have written recently on Christian Domestic Discipline (CDD). The topic touches on a number of important ethical and meta-ethical principles.
On the one hand, I think I have to disagree (just a little) with the Slut: In the broadest sense of "consent"—the sort of consent we apply specifically to criminalization—any activity that a participant actively and directly agrees to for whatever reason short of threat of immediate violence must be viewed as consensual.
There are some extreme lifestyles such as Gorean sex slavery within the BDSM community. Most ordinary people might well see such lifestyles as disagreeable and morally objectionable. But the key consideration is that these lifestyles emerge to satisfy the full inner subjective nature of the participants. In the non-Christian BDSM community we typically see that the ideology is constructed to conform to the participants' inner nature: People construct, adopt and elaborate a "Gorean" ideology to match their subjective nature; they do not typically engage in Gorean slavery because they are convinced of its objective truth.
Another ethical standard that is seen throughout the BDSM community is that the greater the power exchange within a game, the stronger the requirement to negotiate the limitations outside the game, in an environment and context structured to strongly establish and reinforce the equality of the participants.
We don't see either of these ethical principles within CDD. Reading the blogs of some of the submissive victims (and I use the word "victim" intentionally), it seems very clear that they do not participate in their lifestyle purely because it fulfills their full inner subjective nature. Rather, a strong component derives from the delusional conviction that the (suitably cherry-picked) prescriptions of the Christian Bible are literally true. They are convinced that this lifestyle is true and normative without regard to their full inner nature. While there is no immediate, temporal coercion, there certainly seems to be a degree of "supernatural" coercion.
Furthermore, the negotiation of the limitations of this lifestyle never appears to occur in a purely egalitarian context: Even "outside" the game, the husband negotiates from a position of power and authority conferred from the Bible.
While we must view CDD as consensual in the broadest sense, it is clearly not rationally informed consent.
From an purely objective standpoint, of course, every activity—even outright violent coercion—happens according to the totality of the inner nature of the participants. If I give my wallet to an armed robber, it is because I value my life more than my money; the robber values my money more than my life. To an purely ethically neutral observer, these are just facts from which one can construct scientific theories that accurately predict future behavior.
But, of course, none of us are Vulcans* or computers. We are not ethically neutral, we are not purely objective. We value certain states of others' minds over their alternatives. One important state of mind to which I attach tremendous value is belief in the truth: I actively condemn others' desire to be deluded, and I'll equally deprecate any choice which follows from that desire.
*It's arguable that even Vulcans have arbitrary values, their lip service to purely logical analysis notwithstanding.
Because I also value personal autonomy, however, I won't support legal coercive measures to correct a situation—even a situation I will verbally condemn—unless the participant actively and directly desires the intervention of society. By contrast, the victim of an armed robbery does in fact desire assistance, and since I disapprove of the perpetrator's value system, I'm happy to help. As much as I condemn and deprecate CDD, unless the wife actively wants out of the relationship, and unless the husband physically forces her to stay, I feel helpless to intervene directly.
One reason I condemn religious moderates is that they necessarily and fundamentally undermine the strongest philosophical argument against something like CDD: They fail to condemn the delusion itself which differentiates between CDD and rationally informed BDSM. They condemn CDD, of course, (and good for them, I guess) but why? They cannot condemn CDD because it is based in delusion; it is based, after all, on the same sort of delusional thinking that they themselves explicitly endorse. They must, I suppose, condemn it only because they condemn dominant/submissive lifestyles in general (or because it is based on the "wrong" arbitrary assignment of metaphor to scripture).
But by condemning all dominant/submissive lifestyles, they must condemn rationally informed consensual BDSM as well, which entails two troubling consequences: They must deny the primacy of rationally informed consent, and they must deny the primacy of a full expression of one's inner nature*. Without condemning the delusion itself, the religious moderate must, to condemn CDD, condemn small-ell libertarianism and humanism itself, in favor of authoritarianism and the value of conformity. The religious moderate is letting into the tent the nose of a particularly odious camel.
*That does not, of course, in any way compromise the expression of anyone else's inner nature.
To condemn CDD without condemning BDSM under rationally informed consent, someone such as myself must condemn the whole edifice of delusional brainwashing which constitutes modern religion, which necessarily condemns the religious moderates in the same breath. Happily, I'm willing to do so.
On the one hand, I'm pleased that religious moderates approve and disapprove of most of the same things I do—they've retrojected on their God most of the same sort of humanist values that I hold directly. Most, but not all, however: By definition, they cannot retroject on the authority of their God most important meta-values of humanism: anti-authoritarian libertarianism and the universal condemnation of human suffering.