Many believe that the question of whether an act is right or wrong is to be settled by a religious doctrine; but the difficulties are still greater in this direction. In the beginning, this involves a thorough and judicial inquiry into the merits of many, if not all, forms of religion, an investigation which has never been made, and from the nature of things cannot be made. The fact is, that one’s religious opinions are settled long before he begins to investigate and quite by other processes than reason. Then too all religious precepts rest on interpretation, and even the things that seem plainest have ever been subject to a manifold and sometimes conflicting construction. Few if any religious commands will be, or ever were, implicitly relied on without interpretation. The command, “Thou shalt not kill,” looks plain, but does even this furnish an infallible rule of conduct?
Of course, this commandment couldn’t be meant to forbid killing animals. Nevertheless, there are many people who believe that it does, or at least should. No Christian state makes it apply to men convicted of a crime, or against killing in war, and nevertheless, a considerable minority has always held that both forms of killing violate the commandment. Neither can it be held to apply to accidental killings, or killings in self-defense, or in defense of property or family. Laws, too, offer all grades of punishment for different kinds of killing, from very light penalties up to death. Manifestly, then, the commandment must be understood, “Thou shalt not kill when it’s wrong to kill,” and so it furnishes no guide to conduct. As well say: “Thou shalt do nothing that’s wrong.” Religious doctrines do not and clearly cannot be adopted as the criminal code of a state.