Now man is more than ever separated from God by unbelief, because he has not even true knowledge of God: and by false knowledge of God, man does not approach Him, but is severed from Him.
Nor is it possible for one who has a false opinion of God, to know Him in any way at all, because the object of his opinion is not God.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic God opinion
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

“Therefore unbelief is the greatest of sins. I answer that, Every sin consists formally in aversion from God, as stated above (I-II, Q. 71, A. 6; I-II, Q. 73, A. 3) . Hence the more a sin severs man from God, the graver it is. Now man is more than ever separated from God by unbelief, because he has not even true knowledge of God: and by false knowledge of God, man does not approach Him, but is severed from Him. Nor is it possible for one who has a false opinion of God, to know Him in any way at all, because the object of his opinion is not God. Therefore it is clear that the sin of unbelief is greater than any sin that occurs in the perversion of morals. This does not apply to the sins that are opposed to the theological virtues, as we shall state further on” source