It's a broad truth in IF that the best works dealing prominently with Christian themes are written by non-Christians. Cana is the exception.
The game is presented (very loosely) as a late-Victorian translation of an apocryphal account of the Jugs of Cana, better-known as the water-into-wine miracle. As an obscure servant in the house of the bridegroom, you're tasked with finding more wine for the party and, eventually, in setting up the miracle.
The main thing the game depicts is not setting or plot or puzzle or individual characters, but a community: a community composed of individuals, many of them basically dissatisfied, most with diverging interests, full of conflicts great and small. Fundamentally an attractive community, full of kind, generous, intelligent people, but one which you are not quite a core member of. This goes a long way towards making it feel alive, rather than a tidy little parable.
Gameplay-wise, it's old-schoolish and not immensely intuitive. There are multiple solutions to certain puzzles, which have an impact on the general story, but interaction is not the central interest of the game. Some lines of inquiry rely on quite specific knowledge of the original text, and others are counterintuitive. There's a substantial hint system. Use it.
The game's core moral dilemma is, intentionally, trivial. (Spoiler - click to show)Joshua (Jesus) asks you to fetch some water; it's emphasized by other characters that you must do exactly as he says. But shortly thereafter, you have a choice: in order to save a child's life you have to disobey the literal commands of Jesus. The triviality is the point: anybody with the most rudimentary ethical sense can see the right answer, that literalism can't be allowed to trump straightforward ethics.
The approach to the rest of the story takes a similar attitude: it can't really be construed as an attempt at a strict historical retelling. Instead, it treats the text, story and history as juicy story elements rather than hard facts, and indeed in many places it's conspicuously ahistorical. Characters appear who are unlikely to have been around before the start of Jesus' ministry -- but then, so is the freaking Ancient Mariner, a guy who seems carefully chosen for maximum historical inconsistency.
(In the interests of full disclosure, I should point out that I've played an RPG campaign with Chris as the GM, and he took a highly similar approach there: a joyful, loving appropriation and blending of every story in sight, to the point where navigating the game became as much about interpreting, recognising and playing with the references as about in-character decisions. This led to one of the most fun and sustained RPG experiences I've ever had, which inescapably colours my experience of Cana.)
There's a certain kind of literary Christian who seems more invested in the aesthetic potency of Christianity than in its truth or goodness. Borges loved Christianity mostly because it led to Dante, Chaucer and a thousand strange and beautiful theologies. Cana does not quite fit into this model, though it can certainly be read in that mode: miracles and their significance are not really its central interest. (Indeed, Jesus doesn't quite seem to see the point of the miracle, which is fair enough: setting a party up with booze isn't quite the same order of things as healing the sick.)
Of course, all this presupposes that you actually get a decent proportion of the references. Your actual religious beliefs aren't directly pertinent to whether you enjoy Cana or not: more important is a textual interest in the Gospels, and a sense of humour about them.