In the subsection of Chapter 13 in the Brief Second Edition of Traditions & Encounters entitled “Islam and Its Appeal,” Bentley and Ziegler discuss three things that helped Islam appeal to various Hindu people in India. I will lay out all three of these factors and identify the one that is, in my view, the best answer to the question.
Bentley and Ziegler argue that the Sufis were “the most effective agents of conversion to Islam (p. 254).” They argue that the Sufis were respected by Hindus because they were sincere and because their faith could provide “comfort and meaning” for people’s personal lives. Second, they mention the bhakti movement. This was a movement that tried to erase the distinctions between Hinduism and Islam. They say that this movement helped to spread Islamic values.
However, neither of these says anything about why specific groups of Hindus would be attracted to Islam. Only the third factor that Bentley and Ziegler speak of does this. The third factor is the fact that Islam emphasizes the equality of all Muslims. This was in stark contrast with the Hindu faith with its strict caste barriers. Bentley and Ziegler argue that some groups of Hindus were attracted to Islam because they were of lower status in the Hindu system. They hoped that they would be able to get ahead socially if they converted to Islam. They were also attracted to the idea of universal equality.
Thus, I would say that Islam would be popular among certain parts of the Hindu population because of its egalitarian message.