The Divine Institutes

But some one will say that this supreme Being, who made all things, and those also who conferred on men particular benefits, are entitled to their respective worship. First of all, it has never happened that the worshipper of these has also been a worshipper of God. Nor can this possibly happen. For if the honour paid to Him is shared by others, He altogether ceases to be worshipped, since His religion requires us to believe that He is the one and only God. The excellent poet exclaims, that all those who refined life by the invention of arts are in the lower regions, and that even the discoverer himself of such a medicine and art was thrust down by lightning to the Stygian waves, that we may understand how great is the power of the Almighty Father, who can extinguish even gods by His lightnings.

But ingenious men perchance thus reasoned with themselves: Because God cannot be struck with lightning, it is manifest that the occurrence never took place; nay, rather, because it did take place, it is manifest that the person in question was a man, and not a god. For the falsehood of the poets does not consist in the deed, but in the name. For they feared evil, if, in opposition to the general persuasion, they should acknowledge that which was true. But if this is agreed upon among themselves, that gods were made from men, why then do they not believe the poets, if at any time they describe their banishments and wounds, their deaths, and wars, and adulteries?

From which things it may be understood that they could not possibly become gods, since they were not even good men, and during their life they performed those actions which bring forth everlasting death.