Now all these things which prevent the choosing of sin are effects of the Holy Ghost in us; so that, in this sense, to sin through malice is to sin against the Holy Ghost.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic sin malice
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/18755/pg18755-images.html

Context

“In another way it happens that by reason of contempt, that which might have prevented the choosing of evil, is rejected or removed; thus hope is removed by despair, and fear by presumption, and so on, as we shall explain further on (QQ. 20, 21). Now all these things which prevent the choosing of sin are effects of the Holy Ghost in us; so that, in this sense, to sin through malice is to sin against the Holy Ghost. Reply Obj. 1: Just as the confession of faith consists in a protestation not only of words but also of deeds, so blasphemy against the Holy Ghost can be uttered in word, thought and deed.
Reply Obj. 2: According to the third interpretation, blasphemy against the Holy Ghost is condivided with blasphemy against the Son of Man, forasmuch as He is also the Son of God, i.e. the "power of God and the wisdom of God" (1 Cor.” source