Did witch doctors have real power or was it just a gimmick?
Witch doctors did have real power, not merely a gimmick, but that power was Satanic rather than divine. The context describes Simon in Samaria using sorcery and witchcraft to bewitch people, performing miracles, and being regarded as great, yet his power came from Satan, not God.
Les explains that the power of witch doctors is real and should never be dismissed as a trick. In the account of Simon in Samaria, Simon used sorcery and witchcraft, bewitched the people, and performed miracles, so the people gave heed to him and said he was the great power of God. But Les stresses that Simon was not the power of God; he was the power of Satan. This is nothing new, because when Moses and Aaron went before Pharaoh, Aaron's rod became a serpent, and Egypt's magicians did the same. Yet Aaron's serpent swallowed up the others, proving God's power is greater than Satan's. Even so, Les warns, do not sell Satan short. He recalls missionaries returning from dark, uncivilized tribes and rehearsing the power of witch doctors. They had power; it was not a gimmick; it was Satanic. The same was true of Simon: for a long time he had bewitched the people with sorcery, and they regarded him because of it. The lesson is that such power is genuine but demonic, never divine.