(Original Review, 1981-02-24)
If you're not familiar with the The Orthodox Church's intricacies, don't bother reading the novel. It might also to understand the social context in which Anna Karenina is set, which Tolstoy doesn't explain because he was writing for fellow members of the Orthodox Church who would have understood the particular nuances. For Russian society at the time, an immoral act was one that offended all Creation and therefore God himself - it is quite common for Russian priests even now to admonish those confessing to serious sins by telling them that they are 'spitting in Christ's face'.
If you're into stuff like this, you can read the full review.