Symbolism, Imagery, Allegory
What would you do with a bunch of Jesus statues and posters if you were of another religion? Would you be like Twinkle and think: "Oh how cute!" and display them everywhere? Or would you be like Sanjeev and try to dump the stuff somewhere?
Well, what all this Christian stuff means kind of depends on which perspective you take. If you're like Twinkle, it's not a sign of devout faith; the stuff is like a puzzle or hidden treasure, waiting to be figured or found out at …say…a housewarming party with a bunch of your husband's coworkers.
In other words, for Twinkle, the Christian paraphernalia is another way for Twinkle to show how interesting, surprising, and "wow" (TBH 99) she can be. It's another way for her to be the center of attention: "For the rest of their days together she would keep [the silver bust of Christ] on the center of the mantel, flanked on either side by the rest of the menagerie. Each time they had guests Twinkle would explain how she had found it, and they would admire her as they listened" (TBH 124).
In fact, Twinkle is a lot like these Christian treasures: fascinating, shiny, eye-catching.
If you're like Sanjeev though, the stuff is a threat to your very identity as a proper Hindu and Indian. Even though he's the one to inform his coworker that "[t]here are Christians in India," it's clear that he really wants to show that he's not that kind of Indian (or, even, that kind of American)—he's of the Hindu majority: "but we're not [Christian]" (TBH 92), he reminds his coworker.