In scholasticism, Ibn Taymiyya (1263–1328), who did not accept the Mongols' conversion to Sunnism, worried about the integrity of Islam and tried to establish a theological doctrine to purify Islam from its alleged alterations. Unlike contemporary scholarship, which relied on traditions and historical narratives from early Islam, Ibn Taymiyya's methodology was a mixture of the selective use of hadith and a literal understanding of the Quran. He rejected most philosophical approaches to Islam and proposed a clear, simple and dogmatic theology instead. Another major characteristic of his theological approach emphasized the significance of a theocratic state. While prevailing opinion held that religious wisdom was necessary for a state, Ibn Taymiyya regarded political power as necessary for religious excellence. He rejected many hadiths circulating among Muslims during his time and relied repeatedly on only "Sahih Bukhari" and "Sahih Muslim" to refute Asharite doctrine. Feeling threatened by the Crusaders and by the Mongols, Ibn Taymiyya stated it would be obligatory for Muslims to join a physical jihad against non-Muslims. This not only included the invaders but also the heretics among the Muslims, including Shias, Asharites and "philosophers", who Ibn Taymiyya blamed for the deterioration of Islam. Nevertheless, his writings only played a marginal role during his lifetime. He was repeatedly accused of blasphemy by anthropomorphizing God, and his disciple Ibn Kathir distanced himself from his mentor and negated that aspect of his teachings. Yet, some of Ibn Taimiyya's teaching probably influenced his methodology on exegesis in his Tafsir, which discounted much of the exegetical tradition since then. The writings of Ibn Taymiyya and Ibn Kathir became important sources for Wahhabism and 21st century Salafi theology,