Pro-lifers insist that they are dedicated to peaceful resistance against abortion, but it is important to be clear why they oppose violence. This position must be made known both to those who are pro-choice and those who oppose abortion. I have seen pro-choice people argue that pro-lifers do not really believe that abortion is murder, because if we did, we would all shoot abortionists. Such people need to know that nonviolence is not due to timidity or lack of belief on the part of pro-lifers. There are of course pro-lifers who believe that violence is justified, and sadly, some act on such beliefs. Those who would oppose abortion with violence need to be convinced of their error. Unfortunately, standard pro-life PR lines about peace are unconvincing.
The most common thing said by pro-lifers who try to extoll the peaceful nature of the pro-life movement is, "you can't kill in the name of life." If you think about this statement, you realize that only a pacifist could accept it. In reality there are many situations in which one may kill to defend life. Soldiers, policeman, and executioners kill people to enact justice and save lives. In the case of law enforcement and private citizens acting in self-defense, one might argue that they don't "kill," but shoot at bad guys and then capture them if they survive. However, a confused pro-lifer might attempt such a double-effect justification, saying that they don't mean to kill the abortionist, they just want to stop him from performing an abortion and to do so they had to put a bullet in him. The idea that one can never commit acts of violence to protect life is obviously wrong, and it would not take much for someone to reject this pacifistic argument and move on to justifying violence against abortionists.
Another fallacious argument in favor of peace made by pro-lifers is one of utility. Many say that violence should be condemned because it is counterproductive. We are told that violence will discredit the pro-life movement and cause more abortions in the long run. This argument makes some sense, but it does not address the central moral issue. Someone might accept the premise that killing abortionists will discredit pro-lifers, but kill abortionists anyway because they think the positive consequences will outweigh the negative. We need to leave the utilitarian calculus to the pro-choicers and condemn pro-life violence because it is wrong, not because we think it won't be helpful.
The real reason we must not commit acts of violence against abortionists is simply that vigilantism is wrong. Justice belongs to God. To enact justices, the property, liberty, and even life of a wrongdoer may be taken by the state because it is God's agent on earth. St. Paul says, "Let every
person be subject to the governing authorities. For there is no
authority except from God, and those that exist have been instituted by
God." (Romans 13:1-6) It is true of course that some governments may become so wicked that they cease to be governments. Few would argue that the Nazis had a divine mandate. However, though some governments may be opposed, no private citizen has the right to claim the authority of God and take on the role of the state as executioner. Vigilante acts, no matter how well intentioned, are immoral. Vigilante justice is injustice.