Shush. That seems like a trollpost to me. Let people believe what they wish to believe.
Can't.
Beliefs can be wrong and dangerous to themselves and others.
Sure you can. Beliefs can be wrong, but only the actions they undertake because of those beliefs can be dangerous to others. The practical solution is to eliminate the beliefs, but I can't endorse it as ethically correct. I can't accept stomping on somebody's beliefs because I disagree with them or some possible consequences are bad; that's precisely the same mindset that encourages evangelism. The only thing to do is stop them from taking wrong actions.
You can believe whatever you want. You just can't do whatever you want.
Why cant you exactly discuss someone belief? How is it unethical? I'm for free speech, so I dont see anything wrong with evangelism, just annoying. I'm for freedom of religion, with those combined results in discussion of beliefs. Debating, and dissuading someone from belief that are wrong and or harmful is healthy and nessicarry.
Without said debate/discussion how can you learn the bad belief that stem bad actions? Without debate/discussion how can you learn about others belief?
What are the advantages from supporting passively or overtly wrong belief [a limited example, such as the Four Humors, or the Earth is Flat)?
What are the advantages from supporting passively or overtly harmful belief [limited example, airism, heal by faith, child abuse]?
Why shouldn't you try to improve what you believe in?
How do you improve what you believe in without debate?
On a side way related kinda of way, this 'Its Taboo to Discuss Religious belief is rude/wrong/bad', is a meme defense mechanism relaying its own weakness. Stronger belief systems from my experience don't have this defense mechanism.