English courts judged blasphemy by tone of voice, not by what was said
Under English common law you could attack Christianity or deny that God exists and stay out of court, so long as you did it in decent and temperate language. What the law punished was mockery and scoffing. That rule survived into a successful prosecution as late as 1976, and the offence was only scrapped in England and Wales in 2008.
The word itself comes through Latin from a Greek verb meaning to speak evil of, and the same Latin root gave French blasmer and hence the English word blame. Through most of the Middle Ages heresy worried church authorities far more; blasphemy was treated as the careless outburst of someone drunk or badly behaved. Once the Reformation made the very idea of the sacred contested, the two offences began to look alike.
Penalties could be severe. In 1636 the Puritan Massachusetts Bay Colony made cursing God by atheism a capital crime, and in 1697 Scotland hanged Thomas Aikenhead, aged 20, for denying the truth of the Old Testament and Christ's miracles, the last execution for blasphemy in Great Britain. Norway's law of 1687 also prescribed death, though punishments softened during the following century. William Blackstone summed up the English view that the crime deserved fine and imprisonment because Christianity was part of the law of the land.
The distinctive English test grew out of 18th-century Church of England clergy, who drew a line between sober reasoning about doctrine and the banter and buffoonery they saw in Enlightenment wit. In practice this let the courts pursue people promoting atheism in the 18th and 19th centuries. American appellate courts in the 19th century followed the same precedent, and blasphemy stayed restricted speech in the United States well into the 20th century.
Repeal came gradually. Norway last heard a blasphemy accusation in court in 1933 and removed the final trace of its law in 2015. Ireland abolished its law in 2020 and Scotland in 2021. Even so, as of 2019 about 40 percent of the world's countries still had blasphemy laws, and Italy's penal code keeps the offence.
Source: Blasphemy
