Hassan Abbas, is the Distinguished Professor of International Relations at the National Defense University’s Near East South Asia Center for Strategic Studies in Washington. He has written a book titled 'The Prophet's heir' for which he received support from the National Defense University in Washington DC and the Harvard University Project on Shi’sim and Global Affairs at the Weatherhead Center for International Affairs.
In the conclusion, Abbas, who is Pakistani-American, writes-
The impact of Kharijites and Muawiya’s brand of politics would centuries later be seen in the continuation and increase of the devious actions they had initiated—to an extent creating the modern day extremist groups knowns as al Qaeda and ISIS.
Most sub-continentals of my age know that Oman is perfectly peaceful. Yet its Ibadi form of Islam descends from the Kharijise tradition. There are plenty of Indian and Pakistani people living in that beautiful country.
Muawiya was the founder of the Umayyad dynasty and the man who turned Islam into a great naval power. Urdu speakers in the sub-continent were proud of the Umayyad achievements in Spain. By contrast, one may condemn Yazid- Muawiya's son- who grew up with Christians and was a wine bibber, though rather a good poet.
After 9/11 it was fashionable to blame everything on either Ibn Taymiyya or the Wahhabis or both. But the Saudis dealt successfully with their extremists. Qatar is the other Wahhabi nation. It too appears to be more interested in economic development than creating 'extremist groups'.
Where did Islamic extremism come from? Pakistanis know the answer to this very well. The Pakistani Army had started to use Islam as a 'force multiplier' against both India and Afghanistan in the early Seventies. Bhutto, too, saw an advantage in anathematizing Qadianis. The Iranian revolution and the Soviet invasion of Afghanistan were great pretexts for Gen. Zia, who had hanged Butto, to double down on Islamization. But Generals don't create the economic conditions which lead to extremism. Consider the Sipah-e-Sahaba. It started off as a protest against Shia landlords in Jhang.
Great spiritual and religious personalities who lived long ago may certainly inspire us or lead us to faith. But they bear no responsibility whatsoever for bad economic and social policies. This is not to say that there were no crazy people who believed they were the Mahdi or whatever. But every Society can have a Jonestown or David Koresh.