Scott Klusendorf in his book The Case for Life: Equipping Christians to Engage the Culture
In short, you didn’t come from an embryo, you once were an embryo. At no point in your prenatal development did you undergo a substantial change or change of nature. You began as a human being and will remain so until death. Sure, you lacked maturity at that early stage of life (as does an infant), but you were human nonetheless. ‘Living things do not become entirely different creatures in the process of changing their form,’ writes Greg Koukl. ‘Rather, they develop according to a certain physical pattern precisely because of the kind of being they already are.’
