Dietrich Bonhoeffer on marriage and abortion

Marriage involves the acknowledgement of the right of life that is to come into being, a right which is not subject to the disposal of the married couple. Unless this right is acknowledged as a matter of principle, marriage ceases to be marriage and becomes a mere liaison. Acknowledgement of this right means making way for the free creative power of God which can cause new life to proceed from this marriage according to His will. Destruction of the embryo in the mother's womb is a violation of the right to live which God has bestowed upon this nascent life. To raise the question whether we are here concerned already with a human being or not is merely to confuse the issue. The simple fact is that God certainly intended to create a human being and that this nascent human being has been deliberately deprived of his life. And that is nothing but murder.

Dietrich Bonhoeffer, Ethics, pp. 175-6.