My dear L.,
I have been reading your booklet ‘Christian Behavior.“ I have never felt happy about your view of Christian "policy” with regard to divorce. …
[Y]ou observe that you are really committed (with the Christian Church as a whole) to the view that Christian marriage—monogamous, permanent, rigidly “faithful"—is in fact the truth about sexual behavior for all humanity: this is the only road of total health (including sex in its proper place) for all men and women. That it is dissonant with men’s present sex-psychology does not disprove this, as you see: "I think it is the instinct that has gone wrong,” you say. Indeed if this were not so, it would be an intolerable injustice to impose permanent monogamy even on Christians. If Christian marriage were in the last analysis “unnatural” (of the same type as say the prohibition of flesh-meat in certain monastic rules) it could only be imposed on a special “chastity-order” of the Church, not on the universal Church. No item of compulsory Christian morals is valid only for Christians. … I do not think you can possibly support your “policy,” by this argument, for by it you are giving away the very foundation of Christian marriage. The foundation is that this is the correct way of “running the human machine.” Your argument reduces it merely to a way of (perhaps?) getting an extra mileage out of a few selected machines.
The horror of the Christians with whom you disagree (the great majority of all practicing Christians) at legal divorce is in the ultimate analysis precisely that: horror at seeing good machines ruined by misuse. I could that, if you ever get a chance of alterations, you would make the point clear. Toleration of divorce—if a Christian does tolerate it—is toleration of a human abuse, which it requires special local and temporary circumstances to justify (as does the toleration of usury)—if indeed either divorce or genuine usury should be tolerated at all, as a matter of expedient policy.

Under your limitations of space you have not, of course, had opportunity to elaborate your “policy"—toleration of abuse. … A Christian of your view is, as we have seen, committed to the belief that all people who practice "divorce"—certainly divorce as it is now legalized—are misusing the human machine (whatever philosophical defense they may put up), as certainly as men who get drunk (doubtless with a philosophic defense also). They are injuring themselves, other people, and society, by their behavior. And wrong behavior (if it is really wrong on universal principles) is progressive, always: it never stops at being "not very good,” “second best"—it either reforms, or goes on to third-rate, bad, abominable.
The last Christian marriage I attended was held under your system: the bridal pair were "married” twice. They married one another before the Church’s witness (a priest), using one set of formulas, and making a vow of lifelong fidelity (and the woman of obedience); they then married again before the State’s witness… using another set of formulas and making no vow of fidelity or obedience. I felt it was an abominable proceeding—and also ridiculous, since the first set of formulas and vows included the latter as the lesser. In fact it was only not ridiculous on the assumption that the State was in fact saying by implication: I do not recognize the existence of your church; you may have taken certain vows in your meeting place but they are just foolishness, private taboos, a burden you take on yourself: a limited and impermanent contract is all that is really necessary for citizens. In other words this “sharp division” is a piece of propaganda, a counter-homily delivered to young Christians fresh from the solemn words of the Christian minister.