This book seeks to assess the religiousity and religious tendencies of the Delhi Sultanate rulers. This is an incredibly important period as it not only paves the way for Mogul rule and defines the relationship between rulers and Caliphate central (Baghdad and later Cairo), the Abbasids, it also sheds light on the progression from Caliphate to Sultanate and the implications that had on the Ummah.
The importance of this topic cannot be overstated given the amount of anti-Muslim propaganda amongst Hindus and non-Muslims about Muslim rulers (and indeed Muslims), and the misleading propaganda from ideologically driven Muslims who seek to distort history for whatever agenda of the day.
There are finer details that are up for debate, as are parts of his method; for example, the insistence of seeing things through the lens of the Malfuzaat literature, nonetheless, the vast majority of conclusions drawn and commentary given is convincing and exceptional. Illuminating. Refreshing. Thought-provoking.