I was cautioned by someone that suggesting that Mohammad was not God's prophet is extremely insulting to Muslims.
By that rationale, can I not counter that suggesting that Mohammed is God's prophet is extremely insulting to Christians, Jews, Hindus, Buddists, Athiests, Agnostics, etc.?
Obviously I must think that Mohammad was either crazy or a liar. Otherwise, I'd be Muslim. If I'm wrong, then Allah will punish me.
The difference is that I will not kill or in any way harm someone who suggests that Jesus was not God's Son. I might think that such a person will burn in Hell, but that's not my decision or my doing.