Your question: What makes people divided? My answer: Everyone is divided from the first. I have been divided from you since we were born. We are not the same people.
Your question: How can you fix it? My answer: You don't have to fix it. We just only have to admit the difference. What's the problem about the difference of religion, culture, people, countries? Everything is different from yours. Even twin sisters are different each other. They looks like the same, but they are different people.
Ruling the difference out is always used by people who want to be superior. They think that being superior is the reason of life. No, it's wrong. Being superior is sophistry to start the war. You don't have to try to divide the world. Your world itself is different from the other's. You can't change nor fix it.
Good topic always, Sarah. I enjoyed it. Thank you.