unity and of the moral challenge generated by their pious idealism still weighed heavily on Muslim political and religious thought, however. Even if the Kharijites could no longer threaten, their ghosts still had to be answered. The Ibadis are the only Kharijite group to survive into modern times. Ibn Taymiyyah Modern Islam Salafism and Wahhabism The Salafiyya movement is a conservative, Islahi (reform) movement within Sunnī Islam that emerged in the second half of the 19th century and advocate a return to the traditions of the "devout ancestors" (Salaf al-Salih). It has been described as the "fastest-growing Islamic movement"; with each scholar expressing diverse views across social, theological, and political spectrum. Salafis follow a doctrine that can be summed up as taking "a fundamentalist approach to Islam, emulating the Prophet Muhammad and his earliest followers—al-salaf al-salih, the 'pious forefathers'....They reject religious innovation, or bidʻah, and support the implementation of Sharia (Islamic law)." The Salafi movement is often divided into three categories: the largest group are the purists (or quietists), who avoid politics; the second largest group are the militant activists, who get involved in politics; the third and last group are the jihadists, who constitute a minority. Most of the violent Islamist groups come from the Salafi-Jihadist movement and their subgroups. In recent years, Jihadi-Salafist doctrines have often been associated with the armed insurgencies of Islamic extremist movements and terrorist organizations targeting innocent civilians, both Muslims and Non-Muslims, such as al-Qaeda, ISIL/ISIS/IS/Daesh, Boko Haram, etc. The second largest group are the Salafi activists who have a long tradition of political activism, such as those that operate in organizations like the Muslim Brotherhood, the Arab world's major Islamist movement. In the aftermath of widescale repressions after the Arab spring, accompanied by their political failures, the activist-Salafi movements have undergone a decline. The most numerous are the quietists, who believe in disengagement from politics and accept allegiance to Muslim governments, no matter how tyrannical, to avoid fitna (chaos). The Wahhabi movement was founded and spearheaded by the Ḥanbalī scholar and theologian Muhammad ibn ʿAbd al-Wahhab, a religious preacher from the Najd region in central Arabia, and was instrumental in the rise of the House of Saud to power in the Arabian peninsula. Ibn ʿAbd al-Wahhab sought to revive and purify Islam from what he perceived as non-Islamic popular religious beliefs and practices by returning to what, he believed, were the fundamental principles