It is unclear to me how the text's overarching themes of reversal of hierarchy and subversion of contemporary mortal concepts of power could be made more explicit.
How can we bring this understanding of the text's overall direction back to bear on the narrative of Jesus and the children?
Here a bit of social context helps a great deal. John Dominic Crossan provides a useful account of the ideas at hand. (As with all other historical and exegetical claims, there are complexities and counter-interpretations available here; however, my reading on this passage suggests that Crossan's account is not particularly unusual, even if it is especially vivid.) After quoting from an ancient Egyptian letter in which a husband, in the context of some tender words for his wife, casually instructs her to kill the baby with which she is pregnant if that baby turns out to be a girl, Crossan elaborates that:
[The letter] shows us with stark clarity what an infant meant in the Mediterranean. It was quite literally a nobody unless its father accepted it as a member of the family rather than exposing it in the gutter or rubbish dump to die of abandonment or to be taken up by another and reared as a slave... Notice those framing words [in Mark's account of Jesus and the children]: touch, took in his arms, blessed, laid hands on. Those are the official bodily actions of a father designating a newly born infant for life rather than death, for accepting it into his family rather than casting it out with the garbage. (Crossan, 1994, Jesus: A Revolutionary Biography, pgs. 63-64. See also Crossan, 1991, The Historical Jesus: The Life of a Mediterranean Jewish Peasant, pgs. 267-69.)
Crossan's reading places the account of Jesus and the children squarely in the literary vein of the rest of the chapter. It is a text about rejecting contemporary allocations of power, disavowing privilege -- in this case, the patriarch's privilege to arbitrarily exclude children from the family -- and placing oneself on an equal footing with the traditionally marginalized.
Here, with this egalitarian theology from Jesus in hand, we are prepared to return to the question of abortion. When an adult chooses to abort a fetus, can there be any question that an act of power has taken place? The fetus has no autonomy, no control or influence over any adult decision. By contrast, adults and particularly pregnant women have effectively unlimited power over the fetus.
I do not mean by these statements that women should have such power because the fetus is part of their body; these claims are intended as descriptive rather than normative. If the woman chooses to eat well, that provides the fetus with an ample supply of nutrients. If not, then not. If the woman chooses to subject the fetus to drugs or medication, the fetus will be subjected; no choice or influence are available. Finally, if the woman decides to abort the fetus, then the fetus will be aborted. The power relations are clear and nearly as one-sided as can be imagined.
When such power relations exist, what does Jesus demand of the powerful individual? Self-sacrifice and self-subordination. Rather than exercise the power to abort the fetus, Jesus challenges us to abjure that power. He asks us to make ourselves the servant of the weaker party, to reverse the natural and socially-constructed power relations that give us control and the fetus pure subordination. Abortion is unethical, in this Markan light, not because it is murder; the question need not arise. We conclude instead that abortion is a wrong decision because it is a failure of egalitarianism. It is an act of privileging the relatively powerful adult over the absolutely powerless fetus. It is a failure to follow his model of accepting the powerless and marginalized child into our family.
Let us turn now to the related but separate question of whether we ought to favor state action to make abortion illegal, difficult to obtain, or something similar. I think the same criteria apply; in interactions between the relatively powerful and the relatively marginal, Jesus would have the powerful surrender their control and influence to the outcast. But in this interaction between the state and a pregnant woman who, for whatever reason, has chosen to seek an abortion, who has the power and who is the subordinate?
Even in a democracy, an individual woman clearly has less power than the government. Indeed, any individual always has less power than the government. The deciding factor here, in applying the ethics Jesus taught us, is to determine whether the exercise of government power over women's decisions about abortion reinforces established hierarchies and tends to perpetuate the subordination of a traditionally subordinated group. Does this act reinforce and reinscribe the sins and power of earlier generations?
I think it does. Women in our society and many others have long been subordinated to men in large part through collective social control of their sexuality. The patterns are numerous and well known. They persist with us even up to the present. When two teenagers conceive a child, which of the two of them generally receives the majority of the social punishment, including shame, lost economic potential, and loss of peer-group support? America, along with many other countries, long had an ethic in which it was considered shameful for a woman to have lost her virginity before marriage, but the same rules have not always applied for men -- and almost never to the same extent. If abortions are made illegal, will this not constitute yet another instance of society subordinating women by stigmatizing and controlling their reproduction?