Ibn Taymiyya's main point, countering less rigid thinkers like al-Ghazzali, was that the goal of human life is not to know God, nor is it to speculate about God (the goals of theology); nor is the goal to love God. The goal is to serve God through worship and obedience. Since 935, emphasis had grown steadily on recognizing the authority of traditional doctrines (taqlid : tradition, or unquestioning adoption of previous authority) rather than on fresh interpretations to fit the times or new circumstances (ijtihad : independent investigation). Ibn Taymiyya wrote:
"'The religion of Islam turns on these two principles: worshipping God alone and worshipping Him by what He prescribed. He is not served by innovation...It is not permissible when guilt has been established by proof or by witness to suspend the legal punishment, whether by remitting it or by substituting a fine or any other thing: the hand of the thief must be cut off, for the application of the punishments is one of the acts of religion like the jihad in the Way of God.'" (quoted in John Alden Williams, The Word of Islam (Austin, Texas, 1994), 164f.)
Many twentieth century extremist militant movements allowed their thought and behavior to be guided by Ibn Taymiyya's classic and literal interpretation of jihad as holy war against all non-Muslim infidels. He wrote in his al-Siyasa al-shariyya fi Islah al rai'i wa al-ra'iyya ("Governance According to God's Law in Reforming Both the Ruler and his Flock"):
"'The command to participate in jihad and the mention of its merits occur innumerable times in the Koran and the Sunna. Therefore it is the best voluntary [religious] act that man can perform...Jihad implies all kinds of worship, both in its inner and outer forms. More than any other act it implies love and devotion for God, Who is exalted, trust in Him, the surrender of one's life and property to Him, patience, asceticism, remembrance of God and all kinds of other acts [of worship]...Since lawful warfare is essentially jihad and since its aim is that the religion is God's entirely and God's word is uppermost, therefore according to all Muslims, those who stand in the way of this aim must be fought.'" (quoted in Rudolph Peters, Jihad in Classical and Modern Islam, Markus Wiener Publishers, Princeton, N.J.,1996, 47-49.)