Has anyone come up with this theory pertaining to morals?

Warning, this may be confusing at first. Now, is it possible that every human is good? And that they always do what they think is right? For example, during the witch hunts of the 1600's, people would capture other people, who they thought were witches, and burn them at the stake. This is brutal without a doubt considering that now we know that those people actually weren't witches. However, if we absolutely believed that these people were witches and that they would ultimately destroy mankind, would we not do the same? I believe that morals may be a matter of perspective and people of the other perspective view the acts of the original as atrocities. I also believe that the path to true morals is logical and correct reasoning. Another example. If there is a serial killer who brutally kills his victims, we would view his actions as atrocious. However, if he believed that he killed certain people in order to save mankind, would his morals not be strong? He is wrong about his victims being dangerous individuals who will lead mankind to its ultimate doom but he doesn't know that.(He would probably be messed up in the head but he still did what he thought was right) My point made short is that people do what, in their perspective, is right. Also, in order to be a bad person, you must do what you think is wrong while thinking that there will be no positive outcomes for you or the rest of mankind. In that case, there would be no motivation to do the action in the first place, but people only do things if they think something positive will result from that. (Whether it is world peace, happiness throughout the World, or even happiness with one's self/family/friends)