Blasphemy (Gr. , ), in law, has been judicially described (20 Pickering's Reports, 213) as "speaking evil of the Deity, with an impious purpose to derogate from the divine majesty, and to alienate the minds of others from the love and reverence of God. It is purposely using words concerning God calculated and designed to impair and destroy the reverence, respect, and confidence due to him as the intelligent creator, governor, and judge of the world. It embraces the idea of detraction when used toward the Supreme Being, as calumny usually carries the same idea when applied to an individual. It is a wilful and malicious attempt to lessen men's reverence of God, by denying his existence, or his attributes as an intelligent creator, governor, and judge of men, and to prevent their having confidence in him as such." The punishment by the Jewish law was death. Wherever Christianity is the prevailing religion of a country, whether established by law or not, blasphemy is so far noticed by the law that contumelious reproaches of Jesus Christ, profane and malicious scoffing at the Scriptures, and exposing any part thereof to contempt or ridicule, are regarded as blasphemy and punished accordingly.

In England it is a felony at the common law, punishable by fine and imprisonment. In the early legislation of the American colonies death was denounced as the punishment for this offence, but fine or imprisonment, or both, are now substituted. It has sometimes been argued that the punishment of blasphemy by the state is inconsistent with the religious equality and freedom which are a part of the American constitutional law; but this doctrine has not obtained in the courts, which have always held that one who maliciously makes use of language calculated to have an evil effect in sapping the foundations of society and of public order, may properly be punished as an offender against the state. But a fair discussion in a decorous manner of any controverted point or doctrine of religious belief stands on very different ground, and is innocent; the evil motive being essential to this offence. Profane swearing is a species of blasphemy, but more lightly punished.