A local brother is a bit confused – he’s read in a book somewhere that Ibn Taymiyyah repented and calls him Shaykh Ibn Taymiyyah al-Hanbali. I asked some scholars and they said he’s a kāfir?
The reports concering the tawbah of Ibn Taymiyyah are mixed and inconclusive, leading to some ʿulamā’ declaring him to be a kāfir [disbeliever] and murtad [apostate]. In this regard, ʿAllāmah Imam b. Ḥajr al-Haytamī Makkī’s (رحمة الله عليه) work – Fatāwā Hadīthiyyah – seems to indicate towards the takfīr of Ibn Taymiyyah.
Our Imām and Master, Imām Ahmad Ridā Khān (رحمة الله عليه) concludes upon his research however, that Ibn Taymiyyah was a misguided individual, but not a kāfir.
In either case, it is important to avoid using conventions of respect when referring to Ibn Taymiyyah – and as such, he is neither Shaykh nor Shaykh al-Islām, nor should supplications of Divine pleasure or mercy be invoked at the time of his mention.
Allah knows best.