And we are not to believe in demons, although Celsus urges us to do so; but if we are to obey God, we must die, or endure anything, sooner than obey demons. In the same way, we are not to propitiate demons; for it is impossible to propitiate beings that are wicked and that seek the injury of men. Besides, what are the laws in accordance with which Celsus would have us propitiate the demons? For if he means laws enacted in states, he must show that they are in agreement with the divine laws.
But if that cannot be done, as the laws of many states are quite inconsistent with each other, these laws, therefore, must of necessity either be no laws at all in the proper sense of the word, or else the enactments of wicked men; and these we must not obey, for “we must obey God rather than men.” Away, then, with this counsel, which Celsus gives us, to offer prayer to demons: it is not to be listened to for a moment; for our duty is to pray to the Most High God alone, and to the Only-begotten, the First-born of the whole creation, and to ask Him as our High Priest to present the prayers which ascend to Him from us, to His God and our God, to His Father and the Father of those who direct their lives according to His word. And as we would have no desire to enjoy the favour of those men who wish us to follow their wicked lives, and who give us their favour only on condition that we choose nothing opposed to their wishes, because their favour would make us enemies of God, who cannot be pleased with those who have such men for their friends—in the same way those who are acquainted with the nature, the purposes, and the wickedness of demons, can never wish to obtain their favour.
Source: Against Celsus (New Advent)