Pro-abortion and pro-euthanasia arguments presume an idea known as developmental personhood, the philosophical idea that human personhood and human life are separate categories of being and only human persons deserve protection but human life itself does not necessarily deserve protection.
While human life is a simple matter of biology, personhood is a debated notion based on cognitive abilities, self-directed choices, emotional response, and the ability to interact with others. Based on this view, humans develop into beings which possess the abstract concept of “personhood.” Of course, if humans develop into persons, it is also potentially possible to develop out of being a person, meaning a sick person suffering from dementia or in a comatose state at the end of life may no longer be a person. Personhood is a character trait that comes and goes based on our human abilities.
Central to the developmental personhood view is the bifurcation between the categories of human life and human persons, and this can be confusing for Christians since we use the terms human life and human person as synonyms. For the developmental personhood view, the words life and person are not synonyms but are completely separate categories.
The view does not deny that human life begins at conception; the view denies that human personhood begins at conception, and only persons get legal protection. Since the pre-born human is not a person, it is, from their perspective, morally permissible to end the life of a prenatal infant. Likewise at the end of life, someone may cease being a “person” before his or her biological life ends, and thus euthanasia would not be killing a “person.”
The Bible teaches that all humans are made in the image of God and that the image of God is a status and not a function and it is a status granted to humans by their creator and not a status humans give to themselves. Nor is it a status humans grow into; to be human is to be in the image of God. The ethical value of human life does not come from humanity but from God. In contrast, the developmental personhood view stops seeing some of our neighbors as humans, and thus some people become expendable.
In this way, the developmental view is the very opposite of a stance which dignifies the weakest and most defenseless. The Biblical doctrine of the image of God speaks to the innate dignity and worth of each human life, a worth not contingent on anyone’s ability, but based in the Creator’s declaration. If a culture devalues life on one end of the spectrum with abortion and on the other end of the spectrum with euthanasia, everyone in between should take warning.