Most of them want to be God, so they decide what is right and wrong according to their desire. So, in a way, most of them believe they are okay -- by their own moral standard. The sociopath tells himself he is doing you a favor by defrauding you so that you might learn a lesson. The cheating wife tells herself that some imagined slight justifies her actions.
If you think you have your own version of right and wrong that conflicts with God, then you are one of them.