A brief addendum to Steven’s previous note: Irenaeus mentions the use the Carpocratian gnostics put to images in his day:
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.