Humans on the whole, are good creatures. The ones who aren't though, are the ones who like power over others. As we know from history, they will go to great lengths and are willing to commit horrific acts to attain and keep that power.
As for being clever enough, it's not as hard as you may think. The most important elements are;
1. a group of people who believe that they are acting for some greater good (we know you can find people like that - suicide bombers; the ones who built the gas chambers at Auschwitz, etc);
2. control of the media.
Now, you don't need to list anything, but surely, if the basis for your belief cannot be verified, you must question why you believe what you do.