Beware of anyone claiming to want to "do the right thing". This is where the human phenomenon of "self-righteousness" usually rears its head. Self-righteousness usually comes with a desire to control others, to inflict one's sense of right on wrong on the people who behave and think differently.
This means that you need to beware of politically-minded religious people, beware of "patriots", beware of strident law-abiders (they are all hypocrites), and beware of their polar opposites, the strident atheists and religion-haters and anarchists.
Absolute certainty is the problem. People who are absolutely certain of anything usually don’t know a whole lot about that thing.
Another problem is the desperate need that insecure people have for a sense of superiority. This need dictates that they will look for and find it wherever they can. Whoever lacks what they possess is in some way inferior, those who do not think or act like them, are likewise inferior.