Ibn Taymiyyah
The mutakallimun are scholars who engage in ilm al-Kalam (rationalist theology) and they were criticised by Ibn Taymiyyah for their use of rationalist theology and philosophy. He said that the method of kalam was used by the Mu`tazilites, Jahmites and Ash`ari's. Ibn Taymiyyah considered the use of philosophical proofs and kalam to be redundant because he saw the Qur'an and the Sunna as superior rational proofs. Ibn Taymiyyah said that these explanations were not grounded in scriptural evidence such as the philosophical explanation of the divine attributes of God or the proof of God using the cosmological argument. He said that the call to Islam was not made using such methods by the Qur'an or the Prophet and that these theories have only caused errors and corruption. The mutakallimun called their use of rationalist theology "Usul al-Din" "(principles of religion)" but Ibn Taymiyyah said that the use of rationalist theology has nothing to do with the true usul al-din which comes from God and to state otherwise is to say that the Prophet neglected an important aspect of Islam. Ibn Taymiyyah says that the usul al-din of the mutakallimun, deserve to be named usul din al-shaytan (principles of Satanic religion).