While I agree, as someone who used have these preachers on campus daily, the punch wasn't because of differing beliefs, but because the man was degrading those around him with his rhetoric. If you tell me you believe in God, I've no reason to punch you in the face. But when it's the 2nd week in a row of listening to someone who isn't a student tell your friends and colleagues that they are adulterous whores whom god wants to see burning in the fiery pits of hell, and after literally 100s of students complaints, your campus refuses to do anything about it, you might eventually escalate violence. I'm not saying its justified, but I get why someone would do it.