Identity is a central theme in The Night Diary, and is seen as having the ability to bring people together and tear them apart. Although people have multiple identities, those ideas about who someone is exist in a hierarchy and one identity is elevated above the others. Some identities are temporary and fluid, but others are enduring and lead people to hold steadfast to them, allowing identity to define important aspects of one’s existence. For most people living in British India at the time of India’s independence, religious identity surpassed the previously shared sense of identity as British Colonial Indian that had enabled a peaceful coexistence of diverse populations. The elevation of religious identity over all other identities is what necessitated the partition and created separate countries for Muslims and Hindus. It turned the groups into enemies, created over ten million displaced people, and resulted in the deaths of somewhere between several hundred thousand and two million formerly Indian citizens.

Nisha, in the absence of her Muslim mother, identifies as Hindu, not because she is religious but because that is what her father and grandmother are. Papa, a doctor and a secular, or cultural Hindu, believes all people are the same on the inside and does not hold his identity as Hindu above that of Indian citizen, father, or son.