That human life begins at conception is an implicit, but foundational doctrine of Christianity, according to this LifeQuotefrom Lutherans for Life:
“To deny full humanity to a conceptus [embryo] is to deny full humanity to the Savior, ‘qui conceptus est de Spiritu Sancto, natus ex Maria virgine’ (Latin). We worship the coming Savior, we worship the ascended Lord, we worship the resurrected Son of Man, we worship the crucified Lamb, we worship the Boy in the temple, we worship the Babe in the manger, we worship the Conceptus in the womb of the Mother of God. Amen.” Posted on Cyberbrethren a Lutheran Blog.
This is brilliant, decisive, and theologically unanswerable. The Son of God was incarnate when, in the words of the Apostle’s Creed, He was “conceived by the Holy Ghost” and later “born of the Virgin Mary.” If the fetus becomes a human being at some later point–when the soul enters the body, or when the fetus shows brain waves, or some other point–how does that apply to the Incarnation without falling into some kind of modalism or other heresy? Anyone who confesses the Apostle’s Creed must be pro-life when it comes to abortion, embryonic stem cell research, and the rest of it.
And here is a fitting devotion during Advent: Adoring Christ the Embryo.