I don’t think there’s anything else I can say about the ridiculousness of your extremist views that hasn’t already been said.
But on a historical note, most of the early biographers of the Prophet believe that Kab b. al-Ashraf was killed because he went to Mecca after the Battle of Badr and attempted to incite war by telling the Meccans to take revenge against the Prophet Mohammed. This was a special case of treasonous activity; as others have already pointed out, the Prophet did not order the killings of many other people who openly mocked and insulted him during his lifetime.
Frankly, this is why I think it’s ridiculous to attempt to justify blanket statements on Islamic ideology with isolated ahadis or (parts of) verses of the Quran in isolation and completely out of context…though both Muslim extremists and Islam-bashers enjoy doing so as it allows them to twist Islam to suit their respective needs.