Question Fourteen of Chapter Nine of the Third Decade
Whether illusions and divinations of demons are to be believed when the effect occurs
It is asked whether illusions and divinations of demons are to be believed when the event occurs.
It is answered that they are not. The reason is that a demon’s intention is to deceive, and demons do this especially in divinations. For they sometimes speak true things so that human beings may become accustomed to believing them in other matters, in which they afterward deceive them.
Likewise, God alone can know future things, or someone who receives that knowledge from him as from the eternal mirror, as is the case with angels and holy prophets. But demons do not receive it by this way.
And although, because of the great experience which they possess, demons know many things from natural signs, and although the capacity of their intellect is great, it does not follow on this account that faith should be shown to them concerning the certainty of future events, since their knowledge of future things is only conjectural and fallible.
Therefore, just as faith is not to be shown to human beings of whom it is presumed that they have always been accustomed to speak falsehoods, so faith is not to be given to demons because of their will continually to deceive and the darkness of their intellect arising from sin.
These things are from Johannes de Turrecremata, cause 26, question 5, chapter Nec mirum.