The first few chapters of Genesis do not indicate God’s restrictive plan for the sexual conduct of humanity. They have nothing to say about marriage other than to offer an explanation as to why it is that at least some men and women are attracted to each other, and to describe their union as indissoluble. The former is explicit in the text itself, and we have the latter on the very highest authority.
The first few chapters of Genesis consist of contradictory and inconsistent creation accounts cast in the language and culture of their times. They do not describe either history or nature with any degree of accuracy whatsoever. Does this mean I deny their divine inspiration as the opening chapters of the written word of God? By no means! However, the chief divine inspiration — it is pure genius — is in providing two facially contradictory accounts of the same events side-by-side precisely in order to prevent us from taking them literally — even if we did not already know that they were not literally true on the basis of other evidence, historical and scientific. Even absent history and science no one should ever have made that error, for the witnesses do not just not agree, they contradict. (This is not the place to critique the peculiar credence that Scripture can contain no contradictions. Suffice it to say that belief derives from some source hungry for certainty and unable to deal with complex reality and ambiguity.)
To press these accounts into literal applications, as some have done to place limits upon later developments and better understandings, is as false and pointless as taking the visions of Ezekiel or the parables of Jesus as if they were historical accounts rather than exemplary and inspired teaching. That the primeval human was split to form the sexes is a fabulous construct meant to explain attraction between the sexes. It will not stand as “fact” though it has its own “truth.” But it did not happen that way, and the one who told the tale knew that very well, leaving unanswered the obvious problems such as where Cain’s wife came from. He simply wasn’t bothered, as the goal was primarily geared to answer a single question — why do men and women leave their homes to start their own families. Aristophanes did the same thing in Plato’s Symposium, though more broadly acknowledging the range of human emotional and sexual connection as his culture understood it; but there is no reason to think he intended it as natural history any more than the author of Genesis did his mythological tale.
Tobias Stanislas Haller BSG