Sexual morality and global Christianity

Philip Jenkins, one of the leading experts on global Christianity, has written a short essay on polygamy among Christians in Africa.  An excerpt:

For the sake of argument, let us assume that polygamy is widespread among African believers, even within global churches like the Anglican Communion. Given that fact, a liberal American might well ask: By what right can they lecture Episcopalians or Lutherans on sexual morality or insist that homosexuality should bar a person from holding church office? That question makes sense for many Americans in a way that it does not for Africans, because it treats all sexual sins as morally equivalent.

Yes, an African Christian might reply, the domestic practices of some of our members violate church law, and we must struggle to end this regrettable situation. But polygamy in itself does not violate God's law—or else we could not celebrate David, Solomon and all the ancient kings, prophets and patriarchs. The fact that this practice is now forbidden to Christian believers reflects the higher standards of holiness prevailing under the new dispensation. In terms of legal language, polygamy is a mala prohibita offense, something forbidden by law in some societies but not others, rather than something evil in itself, mala in se, which all reasonable people know to be wrong. And while traditional African societies have historically had quite diverse attitudes toward homosexuality, the Bible shows no such tolerance.

For many African Christians, then, polygamy can properly be accepted in some social situations, whereas homosexuality is regarded as sinful always and everywhere. Americans might puzzle over what seems like a contradiction; Africans would likely ask why Westerners can't understand the plain difference. And the arguments will go on.