The Fifth Commandment states, “You shall not kill.” The literal translation of this commandment forbids murder. This is not about a prohibition on killing cattle for food or on killing bugs for our safety, nor is it an absolute prohibition on repelling an aggressor. The commandment means that we do not have authority to murder the innocent. Babies are always in that category. The commandment against directly, deliberately killing a baby or any other innocent person is absolute.
From this commandment comes the prohibition on abortion, at any stage of pregnancy and for any reason whatsoever. The commandment is based on God’s absolute dominion over human life. He alone gives and takes the lives of human beings; He alone governs who comes into the world and who goes out, and when, and how.