A Passage to India may well read like a series of bad parties. We see parties such as: the Turtons' Bridge Party, Fielding's tea party, and Aziz's picnic. All of these occasions are supposed to be about coming together, making some friends, and having a good time, but all of them fail miserably. In the novel, these failed parties serve as allegories for the British Empire in general.
The British Empire as a dud party, you ask? Well, the novel shows that each of these occasions fail because of the British need for exclusion, for hierarchies, for social boundaries, and for establishing an us-versus-them that always sets up an "us" as superior to "them." Racism is an extension of this desire for exclusion, and so is empire, which is based on the principle that "we" are better – more civilized, more modern, more powerful – than "them." Aziz's catastrophe of a picnic is just a spectacular instance of how destructive the British desire for exclusion can be.
But this desire for exclusion isn't confined to the British alone. The novel opens as Moshurram, a Muslim festival, approaches. During the trial, the Moshurram riots were associated with demonstrations in support of Aziz. Before the trial, however, the Moshurram troubles referred to the inevitable tangles between the Muslims and the Hindus about the parade route. The Moshurram riots are an allegory for the religious factionalism that continues to threaten the South Asian subcontinent to this very day.
In contrast to these failed social occasions, take a peek at the Gokul Ashtami festival, which is a festival set up to fail. (We mean fail in the sense of failing to exclude anyone.) The festival celebrates all beings, excluding no one and nothing, not even the tiniest of bugs or the silliest of jokes. In his religious trance, Godbole doesn't get in touch with some higher power; he remembers an old woman (i.e., Mrs. Moore) back in Chandrapore and a wasp.