Jessica Stern argues that ISIS is a "modern phenomenon" and a "new religion". Much the same is said for other radical currents of Islamism, including the Khomeinism of the Islamic Republic of Iran. The point being that the use of the word "medieval" to describe radical Islam is utterly ignorant of historical and current realities. It is, like all other malignant ideologies, an entirely modern phenomenon which contrary to denials was also influenced numerous Western-derived ideas including Communism and fascism.
In a very broad sense, it is quite accurate to describe two Islamic political camps. While we talk about Sufis, Salafists and the Muslim Brotherhood, we can also talk about dividing "Political Islam" into two camps, namely "conservative" and "radical".
The "radical" camp is represented in its most extreme form by ISIS, Al-Qaeda and the Taliban and the so-called "Salafist Jihadism", and in different forms by currents inspired by the Muslim Brotherhood, Jamaat-e-Islami, and in Shiite Islam by the Iranian regime and its proxies like Hezbollah. The "radical" camp can be characterised as "extremist" and "anti-Western" and proponents of terrorism, but in a more sober sense, they are revolutionaries inspired as much by Marxist-influenced Third Worldism as they are by a radicalised form of Islam. They believe in revolution, an overthrow of the existing order and the creation of an Islamist utopia, and are hostile to the societies around them whether in the Islamic World or in the West.
The "conservative" camp includes, likewise, divergent and diametrically opposing strands of Islam such as Sufis and Salafists, as well as traditionalist or "quietist" Shiites. The reason I lump them together is because they share numerous characteristics. Their conservatism is not just social or religious, it's very much political conservatism in the fundamental sense that they reject violence or revolution and cooperate with the established order, and indeed serve to reinforce it. Often "quietism" means religious leaders avoiding direct involvement in politics and leave governing to temporal rulers, but it also means collaboration with the state. Hence they will work within the established political and socioeconomic order - anything from absolute monarchy to parliamentary democracy - rather than oppose it.
With the rise of ISIS, both conservative Sufi and Salafist groups have also devoted resources to refuting radical currents.
This is evident not only in Saudi Arabia and the Gulf states (where conservative Salafists support the monarchies they are ruled by), but also in Egypt and Jordan. In both Egypt and Jordan, the conservative Salafist tradition is represented by the Nour Party in Egypt (who more or less supported the military takeover by Sisi) and by Salafist sheikhs like Ali Al-Halabi in Jordan (who is essentially allied with the Hashemite monarchy of Abdullah II). While diametrically opposed and antagonistic, Sufis also take a similar path. In this respect, both Sufis and Salafists can be deemed representative of a conservative and even reactionary (as opposed to radical and revolutionary) form of Islam.
For us in the West, what does that mean? Many who do not have a nuanced understanding of Islam may not see the difference among them. Many may not see the difference outwardly between Salafist jihadists and ISIS on one hand, and the "loyalist" Salafists of Egypt, Jordan and the Gulf states on the other. There is a very real political and ideological difference between them, an understanding of which is necessary in unscrambling the regional quagmire.