I think that Atticus is saying that the men who came to lynch Tom are good honest people that just don’t yet understand why everyone should be treated the same. I think that it is possible to be someone who could want to do something terrible but still be a good person. Sometimes people just don’t understand everything in life. They misinterpret different situations. The men that wanted to kill Tom don’t yet understand that everyone is alike, no matter the color or our skin. This is their blind spot. When you don’t fully grasp a concept, the way you tell it to others may be the wrong way and so they won’t be able to fully grasp it either.