I'm going to start this post off by qualifying my experience with the show. I only watched the first few episodes and once season 5 started I went back and watched every episode (and finished before season 5 ended somehow). So not watching them as they came out week by week and having built up excitement might be a major factor as to why I don't hate Stranger in a Strange Land as much as most people on this site seem to. But here is a little theory I've cooked up. More of a guess because I admit there are plenty of unexplained holes but here it goes.
One thing that has always stuck with me about this episode is how terrified the hot asian chick who gave him his tatoo was once she did her psychic reading. Also, that the locals were so upset and scared by what she told them she saw that they beat up Jack and made him leave. As some of you may or may not know the title of this episode is the same as what some people claim to be the greatest science fiction novel ever. It is about a man named Valentine Michael Smith that was left on Mars as a child and raised by aliens. He is human nature but possesses alien abilities. So that got me thinking, what if the Jack we know on the show is from an alternate universe? At first I was thinking he passed into this universe as we know it in the pilot at the time his eye opened. That is why he was in the jungle. Then I started thinking about Christian and how we don't know much about his past and how he might know about the island. What if Jack came from an alternate universe as a child as a result of something Christian did on the island? Maybe those locals were so terrified of Jack because he wasn't from this universe. Maybe his wanting to fix things is an indirect result of hime wanting to change things in this universe to be more like they are in the universe he comes from. Maybe his wife died from that car accident in a different universe??
Like I said, I think there are plenty of holes in this theory. But something about that episode made me feel like it was a big mystery as to why they were scared of him and I was quite surprised once I came on to this site to find out that so many people here hated the episode.