The Prescription Against Heretics by Tertullian
Chapter XL.--No Difference in the Spirit of Idolatry and of Heresy In the Rites of Idolatry, Satan Imitated and Distorted the Divine Institutions of the Older Scriptures. The Christian Scriptures Corrupted by Him in the Perversions of the Various Heretics
The question will arise, By whom is to be interpreted the sense of the passages which make for heresies? By the devil, of course, to whom pertain those wiles which pervert the truth, and who, by the mystic rites of his idols, vies even with the essential portions of the sacraments of God. He, too, baptizes some -- that is, his own believers and faithful followers; he promises the putting away of sins by a laver (of his own); and if my memory still serves me, Mithra there, (in the kingdom of Satan,) sets his marks on the foreheads of his soldiers; celebrates also the oblation of bread, and introduces an image of a resurrection, and before a sword wreathes a crown. What also must we say to (Satan's) limiting his chief priest to a single marriage? He, too, has his virgins; he, too, has his proficients in continence. Suppose now we revolve in our minds the superstitions of Numa Pompilius, and consider his priestly offices and badges and privileges, his sacrificial services, too, and the instruments and vessels of the sacrifices themselves, and the curious rites of his expiations and vows: is it not clear to us that the devil imitated the well-known moroseness of the Jewish law? Since, therefore he has shown such emulation in his great aim of expressing, in the concerns of his idolatry, those very things of which consists the administration of Christ's sacraments, it follows, of course, that the same being, possessing still the same genius, both set his heart upon, and succeeded in, adapting to his profane and rival creed the very documents of divine things and of the Christian saints -- his interpretation from their interpretations, his words from their words, his parables from their parables. For this reason, then, no one ought to doubt, either that |spiritual wickednesses,| from which also heresies come, have been introduced by the devil, or that there is any real difference between heresies and idolatry, seeing that they appertain both to the same author and the same work that idolatry does. They either pretend that there is another god in opposition to the Creator, or, even if they acknowledge that the Creator is the one only God, they treat of Him as a different being from what He is in truth. The consequence is, that every lie which they speak of God is in a certain sense a sort of idolatry.