Even unbelief is not sinful unless it be voluntary: wherefore the more voluntary it is, the more it is sinful. Now it becomes voluntary by the fact that a man hates the truth that is proposed to him.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic truth hate
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

“Hence it is evident that hatred of God is chiefly a sin against the Holy Ghost, in so far as the sin against the Holy Ghost denotes a special kind of sin: and yet it is not reckoned among the kinds of sin against the Holy Ghost, because it is universally found in every kind of that sin. Reply Obj. 2: Even unbelief is not sinful unless it be voluntary: wherefore the more voluntary it is, the more it is sinful. Now it becomes voluntary by the fact that a man hates the truth that is proposed to him. Wherefore it is evident that unbelief derives its sinfulness from hatred of God, Whose truth is the object of faith; and hence just as a cause is greater than its effect, so hatred of God is a greater sin than unbelief.” source