Germany 1941, Japan 1941 - what's the difference between 1981 Japan or 1981 Germany? It's the same human brain, you have to accept that people do not DIRECTLY all interact with Hitler or the Emperor of Japan. They interact with memes and messages.
With Islamic Terrorists, Mohammad has been dead for over 1000 years, but the Mosque can still use the POETRY to convince people to become suicide bombers! Words from a man LONG DEAD can manipulate people! Even Nazi followers long after Hitler's death.