Many people have genuinely been delivered from evil, but others have failed to understand the real problems. Evil spirits are at home where there is sin. Demon possession and demonic influence are not the same as sin, but are closely linked with it. The heathen world deals with demons by ceremonies and incantations and magic words. Moral values do not matter.
Sin is irrelevant.
It is a matter of manipulating or appeasing spirits. Much that appears to be Christian exorcism or deliverance ministry is not very different. Some people call in the priest who comes equipped with a prayer book and recites a mass or communion service. Others expect success if they use commands found in scripture to cast out demons. The first two items of armour that he names are truth and righteousness.