Library Eusebius of Caesarea Preparation for the Gospel
Book 4, Chapter 10
Then as he goes on, he refutes the opinions of the multitude, by saying that we ought not to regard as gods those who rejoice in the sacrifices of living creatures. For to offer animals in sacrifice, he says, is of all things most unjust, and unholy, and abominable, and hurtful, and therefore not pleasing to gods. But in speaking thus it is evident that he must convict his own god: for he said just before that the oracle enjoined the sacrifice of animals, not only to the infernal and terrestrial gods, but also to those of the air, the heaven, and the ether.
And whereas such are Apollo's injunctions, yet he, appealing to Theophrastus as witness, says that the sacrifice of animals is not fit for gods, but for daemons only: so that, according to the argument of himself and Theophrastus, Apollo is a daemon and not a god; and not Apollo only but also all those who have been regarded as gods among all the heathen, those to whom whole peoples, both rulers and ruled, in cities and in country districts, offer animal sacrifices. For these we ought to believe to be nothing else than daemons, according to the philosophers whom we have mentioned.
But if they say that they are good, how then, if indeed bloody sacrifice was unholy and abominable and hurtful, could those who were pleased with such things as these be good? And if they should also be shown to delight not only in such sacrifices as these, but, with an excess of cruelty and inhumanity, in the slaughter of men and in human sacrifices, how can they be other than utterly blood-guilty, and friends of all cruelty and inhumanity, and nothing else than wicked daemons?
Now when these things have been demonstrated by us, I suppose that good reason has been rendered for our withdrawal from the practices mentioned. For even to confer the honour of one who is invested with regal dignity among men upon robbers and housebreakers is not holy nor pious, much less to degrade the adorable name of God and His supreme honour to wicked spirits.
Hence we who have been taught to worship only the God who is over all, and to honour in due degree the divinely favoured and blessed powers which are around Him, bring with us no earthy or dead offering, nor gore and blood, nor anything of corruptible and material substance; but with a mind purified from all wickedness, and with a body clothed with the ornament of purity and temperance which is brighter than any raiment, and with right doctrines worthy of God, and beside all this with sincerity of disposition, we pray that we may guard even unto death the religion delivered unto us by our Saviour.
English translation by E. H. Gifford, Eusebii Pamphili Evangelicae Praeparationis Libri XV (Oxford, 1903). Public domain. Digital text via Roger Pearse / tertullian.org.