Here is something an ancient Roman pagan was quoted as saying about Christians:
Now the story about the initiation of young novices is as much to be detested as it is well known. An infant covered over with meal, that it may deceive the unwary, is placed before him who is to be stained with their rites: this infant is slain by the young pupil, who has been urged on as if to harmless blows on the surface of the meal, with dark and secret wounds.
Thirstily--O horror!--they lick up its blood; eagerly they divide its limbs. By this victim they are pledged together; with this consciousness of wickedness they are covenanted to mutual silence.
This quote is from The Octavius of Minucius Felix, an ancient Christian apologetic work in which Octavius, a Christian, debates with a Roman pagan named Caecilius, who makes various nasty allegations against Christians including the above.
In the Middle Ages, all too many Christians made similar allegations against Jews. And, these days, all too many Christians, and some other folks too, have made similar allegations against Satanists, Pagans, etc.