That quote is incomplete. It goes on to explain that the inverted cross is considered satanic by heavy metal aficionados and Satan worshippers. It is particularly offensive when it is a crucifix, as in some films, “The Exorcism of Emily Rose” or “The Exorcist.”
I do not consider the (inverted) Petrine Cross to be satanic, as do the heavy metal fans and satan worshippers. Which category do you fall into?
Others of them employ outward marks, branding their disciples inside the lobe of the right ear. From among these also arose Marcellina, who came to Rome under [the episcopate of] Anicetus, and, holding these doctrines, she led multitudes astray. They style themselves Gnostics. They also possess images, some of them painted, and others formed from different kinds of material; while they maintain that a likeness of Christ was made by Pilate at that time when Jesus lived among them. They crown these images, and set them up along with the images of the philosophers of the world that is to say, with the images of Pythagoras, and Plato, and Aristotle, and the rest. They have also other modes of honouring these images, after the same manner of the Gentiles.” -Irenaeus, Against Heresies 1.25.6
But it is clear to every one that piety, which teaches to worship and honour, is the highest and oldest cause; and the law itself exhibits justice, and teaches wisdom, by abstinence from sensible images, and by inviting to the Maker and Father of the universe.” -Clement ofAlexandria, The Stromata 2.18
So we would now make a remark about the arts of the theatre, about the things also whose authors in the names we execrate. We know that the names of the dead are nothing, as are their images; but we know well enough, too, who, when images are set up, under these names carry on their wicked work, and exult in the homage rendered to them, and pretend to be divine-none other than spirits accursed, than devils.” -Tertullian, The Shows 10
Exodus 20:4 - You shall not make for yourself an idol, or any likeness of what is in heaven above or on the earth beneath or in the water under the earth.
John 4:24 - God is spirit, and those who worship Him must worship in spirit and truth.