I just finished the book, Operation Mincemeat, by Ben Macintyre, which is about an incident in World War II where the British totally deceived the Germans as to the invasion of Sicily. Macintyre had a very interesting observation about deception, which I think is just as appropriate for discussing false teachings.
"Deception is a sort of seduction. In love and war, adultery and espionage, deceit can only succeed if the deceived party is willing, in some way, to be deceived."
And, as I have mentioned before, once people are deceived they will often remain deceived due to their investment in whatever it is they are following - "deception by investment." People who want to be deceived are often hard nuts to crack with the truth. But we must keep trying to do so, nevertheless.