It's a difficult topic because it's so broad, and one has to divide the focus between Hinduism in the abstract (as a set of religious practices and beliefs), and Hinduism as an evolving social identity in the context of historical phenomena: British colonialism, the nationalist movement, various reform and revival projects (Arya Samaj and Brahmo Samaj), Partition, and the rise of contemporary Hindu nationalism post-independence. Most representations of "Hinduism in fiction" tend to be in novels and short stories that are most concerned to engage those historical events, especially the reform movements, the partition, and contemporary communalism. Fewer Indian novelists have aimed to consider Hinduism in theological terms (though some have). That's pretty much as it should be -- prose fiction only came of age in India after British colonialism and Christian missionaries had made their presence felt -- but it might not be the whole story.
Here are some of the authors it seems appropriate to talk about in the essay:
19th Century and early 20th century:
- Bankim Chandra Chatterji (Chattopadhyay)
- British colonial writers like Kipling and Forster (these writers had a major impact on how Hinduism was perceived by both the broader world and often by Indians themselves; many Indian writers wrote in response to Forster, for instance).
- Rabindranath Tagore (Gora stands out as a book where competing
definitions of Hinduism are discussed in the context of the rising nationalist movement in the Swadeshi era)
- Mulk Raj Anand
- U.R. Anantha Murthy (Samskara)
- Premchand (Godaan, short stories like "Sujan the Devout")
Contemporary and Postmodern:
- Salman Rushdie's Midnight's Children
- Ashok Banker's Prince of Ayodhya fantasy novels
- William Buck's re-imagining of the Ramayana
- Githa Hariharan, In Times of Siege
- Manju Kapur, A Married Woman
- Diasporic representations of Hinduism: especially V.S. Naipaul.
I'm curious to know whether people would suggest other authors who might be good, or have favorite passages or books that have interesting things to say about Hinduism, either as a social identity or as theology/philosophy. (If I use your suggestion you'll get an acknowledgment in the essay and a copy of it when it's published.)