I can't understand Israelis. Yes they have been brainwashed but the facts speak for themselves. 5,000 Jews have been murdered since Oslo with at least half of those in the last decade. Most Israelis have either lost a friend or family member to jihad or know someone who has. People can be brainwashed but how can they deny such powerful physical evidence in front of their faces?
I don't know if Judaism has a concept of "natural law" or "creation witness" but to make a long story short, those are principles that say that you do not need to be directly told something from G-d via supernatural revelation or preached to by one of G-d's servants to be held accountable for something. If something is so obviously true just from looking at the world you are supposed to know and internalize it and abide by it.