What is Blasphemy?
'Blasphemy is a word, or a discourse injurious to God, his Saints, or Religion.
It is blasphemy to attribute to God defects which do not, or could not belong to him, such as taxing him with partiality, injustice, or the like.
It is blaspheming God to deny to him that which is his due, such as pretending that He disdains to take care of his creatures, that He takes no notice of the affairs of this world, &c.
It is blasphemy against God to speak with contempt of his divine attributes, perfections, &c.
It is blasphemy of the worst kind to speak disrespectfully of God, even though it be through custom, and the sin is still greater if the blasphemy is spoken in anger, passion, or through contempt.
It is blaspheming God to join to his adorable name certain terms which dishonour him; . . .]
It is blasphemy against the Saints, to mock them, to attribute to them defects or failings, to find fault with the honours rendered to them by the Church, &c.
It is blaspheming Religion, to turn it into ridicule, to blame its practices, to speak ill of the Sacred Scriptures, &c., &c.
Then there are also blasphemies of mind and heart; these are thoughts and desires contrary to the divine perfections or to things which concern religion; such is the blasphemy of the fool who said in his heart “There is no God.” This is a horrible, an execrable sin, and deserving of the most terrible punishment
Blasphemers are no longer stoned to death, nor are their tongues pierced; but let them not triumph the more of that, for the time of chastisement will soon come, when they, wretches that they are, shall receive the punishment due to such crimes.’
St. Jean Baptiste de la Salle, ‘Duty of a Christian towards God’