There is cause and there is effect. The effect is babies; the cause is the act of procreation. In times past, the arena in which this aspect of human life was debated was that of "original sin." Today, the arena in which this aspect of human life is debated is that of "abortion." The abortion controversy and the original sin controversy are theologically the same: the question of the status of the newborn child.
In both these controversies, the issue concerns the definition of what is a human being, centering around the stage of life in which such definition is entirely imposed by others. How can adults define the status of infants or fetuses? Who can define the moment human life begins, the moment at which a collection of human-born cells becomes a person? There is no empirical way to locate that moment; the assignment is, from a scientific point of view, arbitrary. Nor can we empirically determine the status of innocence or sinfulness of fetuses or new-borns. The acquirement of personhood and the acquirement of sin are equally obscure, and arguments over this question may in fact be the means by which different eras attempt to define the same thing. Our forebears were concerned about status before God, hence the origin of sin. We moderns are concerned about legal autonomy; hence the origin of personhood.
In both cases the definition is based upon external ideological, faith and/or social considerations. In both cases, the contestants are missing the mark in the same way. They are displacing the focus of concern from the parents, and the act of procreation, to the child, the result of procreation. They are concerned with the effect and not the cause.
By neglecting the issue of the way of parenting, pro-life folk are for all intents and purposes giving up on the task of reforming society's standards which determine the context for men and women having babies. They are inadvertently committing the error of those who advocate the free distribution of condoms in schools on the grounds that teen promiscuity is inevitable and uncontrollable. Conservatives accept it as inevitable that there will be millions of unwanted pregnancies, i.e. irresponsible procreative acts, and the battle is therefore joined over what to do with all of these fetuses. Conservatives bemoan the millions of aborted fetuses, but do not address the billions of immoral acts of fornication, a small percentage of which produced those fetuses.
As long as pro-lifers concede this issue, they will be locked in the same no-win debate as that lost by those who argued that infants possess original sin but never took it upon themselves to examine or question the nature of the procreative act through which the infant inherited this sin. Once the procreative act is judged good, which American Protestants tacitly do, the resulting infant had to be good. Otherwise God was intervening to make an innocent baby evil. And this is exactly the way the anti-original sin argument went, and it won by appeal to the sentiments.
Similarly, without a radical questioning of the context of procreation, i.e., love and marriage in our society, the flood of unwanted babies will continue and the abortion debate rage. That is, as long as it is legitimate for men and women to enter into procreative acts with neither the intention of creating a child nor even the mutual sense of responsibility for the child which could result, the anti-abortion position is very weak. If man and woman are granted the "right" to have sex immorally and irresponsibly, why shouldn't they have the "right" to rid themselves of the fetus? Both rights have to do with the freedom to do what one wants with one's own body. If conservatives want to address the rights having to do with the effect, they must also address the rights having to do with the cause.
That is, the conservatives lose the battle unless they address the issue of parenting. In the case of original sin, if we say babies have original sin, then we must deal with how they received it in an intelligent way (not palming it off as an act of God). If we say people cannot have abortions, we must deal with the question of how unwanted babies come to be (not palming it off as the way of the world).
It is on this count that Protestants of all stripes are liberals, for the Catholics, in their encouragement of religious celibacy, at least maintain an implicit critique of the procreative act. However, popular Catholic conviction concerning celibacy is waning as Catholic exaltation of marriage rises. In this as in every other arena the Catholics are becoming Protestants.
The conservatives in both cases are accepting this liberal definition of the playing field and therefore are dooming their own cause. Once the liberal assumptions about the ways of parenting are accepted, that is, once we allow the ways of parenting to go unquestioned, we are accepting the liberal norm as to the cause. Once we have done so, there is no way to overcome the liberal argument for the effect, and the best we can hope for is to delay their inevitable victory: abortion is a valid option for sinless but unwanted fetuses.