This is Irving in full-throttle "omniscient narrator" mode. All the craft is here, time jumps, foreshadowing, multiple viewpoints, non-linear structure, etc. The opinionated narrator leads the reader shamelessly through meanders in the plot. Though pace is arguably slow for the first half (of what is a long novel), the reader is amply rewarded with very funny scenes thereafter.
The theme is alienation, ostensibly that of the migrant, one who is not quite at home in the culture of his birth nor in his adopted land. But this theme also embraces the ambivalence the protagonist Dr Farrokh Daruwalla (an orthopaedic surgeon) feels toward Christianity and Catholicism, in particular.
Set predominantly in India, this novel brings to life the colour, smells, beauty, deprivation, harshness, and the conflicted influences and faiths at work in that land. Of course, being an Irving novel, there is nothing ordinary about Daruwalla's life. Continually drawn back to India to help crippled children, the doctor becomes fascinated by dwarfism and hopes to find the genetic basis for this condition through collection and DNA analysis of blood samples. This in turn leads him to the places where dwarfs are most readily available: circuses.
There is also a "writer's element" to the story, with the surgeon seeking creative expression through screenwriting for the Indian cinema. However, the surgeon's motives in this are again less than straightforward. He is creating a part - and an identity - for his stepbrother John. And John had a twin (Martin), separated at birth, who trains to become a Jesuit priest, bringing this review back to the above mentioned comedic scenes. Martin is a hoot.
This is an excellent read. Immerse yourself; don't rush at that cliff-edge of pages. In a fast-changing, messy world, spending time in this circus novel is perhaps as good a place to be as any. One way or another, we are all foreigners now.