Capital punishment is not murder. In those few microscopic cells, there is divinely placed potential that is meant to be given a chance to live and to glorify God. If that life is cut short, God's gift has been robbed from that baby. On the other hand, when an adult in his right mind murders another person, he has done irreparable harm to that person. Second, the government is valuing life very highly.
Murder demands justice.
To do any less is to cheapen the life of the murder victim. If someone is murdered and the state refuses to punish that murderer by capital punishment, then they are saying that the murderer's life is more valuable than the life of the one murdered. The Bible supports capital punishment. Many places in the Old Testament God explicitly states that certain crimes require capital punishment. In the New Testament, God tells us that the government is charged by God with the punishment of wrongdoers, and he includes capital punishment in that mandate.