There was a lot of discussion, once again, about abortion during this election cycle. Hence, the same arguments were used by both sides. The pro-choice group tends to diminish the idea that the fetus is human, so much so that it makes abortion a matter of "women's health," and a right for the woman to do whatever she wishes with her "own body"--thus emphasizing the idea that the fetus is a non-human entity and only the woman remains. Pro-life groups counter this by trying to argue that the fetus is, in fact, a distinct human from the mother, a scientific fact of course that seems to escape our society of supposedly scientifically-driven moralists.
To start off, the new argument is valid. Neo-evangelicals typically argue over whether the fetus is a human being with the same rights as any other human being. But this is more of a legal way of looking at the question. And, of course, this is where neo-evangelicalism needed to go once it started making an argument in the sixties that there were legitimate uses of birth control and abortion. It switched up on abortion, largely due to the work of Francis Schaeffer and John Warwick Montgomery, but it wanted to maintain its stance on birth control in general, and so a new path of argumentation against abortion, but for birth control, was forged.
But the historical argument was never concerned with whether the fetus had a soul or was a full human being yet. Those questions were completely irrelevant. Many Christian leaders believed the soul may not have been placed within a child until later in the womb or even as late as the birth itself. Again, it was irrelevant.
The reason why it was irrelevant is because the historical Christian argument against abortion, which also included the reason why they rejected contraception, was that it was a misuse of sex and a hindering of a human life that God may purpose to exist. In other words, it was an anti-creational act against humanity, against the role of the image, against creation and for chaos. It was anti-life and therefore pro-death. Hence, the use of sex that did not allow for procreation, either by contracepting or aborting the human that was projected to exist through the sexual act, is a sexually immoral act; and to willfully engage in a sex act that prevented a human being that may come into existence through it from coming into existence was an act worse than murder, as it did not even allow a human to exist in the first place.
Most Christian teachers saw abortion as the killing of the human that was coming, or had already come, into existence; and hence, it was murder; but since they considered contraception as a practice worse than murder, or at least its equivalent, it was irrelevant to argue whether the fetus was yet human.
Christians, as the people of God who worked toward life in all of their practices, including their sexual practices, had an obligation to be creational and work toward the human life God expressed was His revealed purpose of sex in creation. To work against it, was to be a chaotic agent, an agent of death, an agent that worked against God's purposes for the sexual act and against human life and preservation upon the earth. Hence, only the wicked use their sexual acts to prevent children from coming to be. They are the murderers of humanity. The sexually depraved, who distort sex into something that is merely for pleasure and self-fulfillment. There is no lifting up of the Creator in the obedience of Genesis 1:28-31.
Hence, anyone who aborted a fetus was participating in one of the most evil acts one could. It's why the Fathers considered it worthy of judgment. It's why Luther considered it a corruption of mankind for which eternal judgment was rightly handed out; and why people like Calvin believed one would definitively go to hell for the sin.
The argument is that such people do these evils because they are not people of life, i.e., Christians, at all; but rather destroyers of humanity, whether it be that the humanity they destroy already lives or is coming to be. Whether a person purposes to prevent a human life or destroy a human life that already exists was simply irrelevant to the historic Christian argument. It's a valid argument to make when discussing the legality of such a thing, but that should not be confused with the moral argument that has been historically made against it.
Of course, evangelicals won't like this argument, simply because it doesn't just condemn abortion, which many already see as an evil, but also contraception, which most within the past fifty years have come to believe is amoral and a matter of reproductive choice.