If a firearm is used by a criminal or psychopath with evil intentions, then it is a tool for evil. But if it is used for good (to defend life and property), then it is a tool for good. A firearm by itself has no sentience, no volition, no moral force, and no politics. The proper term for this is an adiaphorous object--something that is neither good nor evil. A firearm is simply a cleverly-designed construction of metal, wood, and plastic in the form of a precision tool.