To put it in personal terms: why does incest horrify me in a way that homosexuality does not? Because I have, and like, gay friends; people who commit incest turn my stomach.

Al Mohler has posted some fascinating reflections on the case of incest involving a Columbia University professor and his adult daughter (read here: http://bit.ly/gZtrE2)

That the case involves a consensual relationship between two adults makes it somewhat more complicated than one might first think; and it looks set to be the context for some very powerful legal arguments for the legitimacy of incest, given the fact that legislation about sexual mores has over recent decades tended to root its arguments in issues of consent and adulthood.

It also lays bare somewhat the fact that questions of morality are increasingly functions of taste and aesthetics, rather than truth. To put it in personal terms: why does incest horrify me in a way that homosexuality does not? Because I have, and like, gay friends; people who commit incest turn my stomach.

So here is the challenge to mainline churches: go back and read the reports you did on human sexuality and the legitimacy of homosexuality, and see if there is anything there which you might be able to use to argue against incest between consenting adults. If there is nothing, then ask yourselves whether you should object to the members of your church practising the same.

Indeed, switch `gay’ or `homosexual’ and their cognates for `incest’ and its variations. Does the logic now fail? Does the argument collapse? Are you comfortable with that? If not, why not? Bigotry? Insecurity? Lack of love towards those whom God made different?

As for the rest of us, be prepared to have even your love for your children or your parents sexualised. Remember Lisa Miller’s piece in Newsweek magazine (commented on in Ref21 here), with its undercurrent of accusations of sexual insecurity and bigotry against those who object to gay marriage and its insinuations about the friendship between David and Jonathan?

The article works perfectly well, logically and hermeneutically, if you switch `homosexuality’ for `incest’ and replace the paragraph on David with one about Lot and his daughters. Prepare for a world where the language of love of a father for a daughter or son carries inherently sexual connotations, and where denial of the same is a sign of your insecurity.

It is all so reminiscent of the world envisaged by Nietzsche’s madman in The Gay Science 125, as one friend immediately commented to me after reading Al’s blog… And yet in a sense it isn’t like that at all.

Nietzsche’s madman sees clearly the chaos unleashed by the God-killers on the world; but– and here is the crucial point so often missed by those who cite this passage — unlike the smug, polite, civilised, and ultimately blind God-killers around him and at whom his polemic is aimed, he is awed and terrified by what he and they have unleashed upon the world, by the responsibility they have taken onto their own shoulders, by the suddenly fluid and evasive nature of all meaning and value, by the fact that taste is now truth, and, above all, by the terrifying power they now have arrogated to themselves. He knows there are no longer any external limits to human creativity.

But we are not surrounded by Nietzsche’s madmen in the press or in law courts or in the mainline pulpits; we are surrounded by precisely those smug men who have killed God and yet know not what they have done.

Carl R Trueman is Departmental Chair of Church History at Westminster Theological Seminary in Philadelphia. He has an MA in Classics from the University of Cambridge and a PhD in Church History from the University of Aberdeen. He is editor of the IFES journal, Themelios, and has taught on the faculties of theology at both the University of Nottingham and the University of Aberdeen. This article is reprinted from the Reformation 21 blog and is used with their permission. http://www.reformation21.org/blog/