Keeping Faith is primarily a story about a young girl who suddenly starts seeing God and performing miracles. My impression was that readers would be allowed to come to our own conclusions about this (whether it was real, invented by Faith, invented by her mother for attention, etc.), but it doesn't work out that way: clearly, within the context of the story, Faith is healing people, experiencing stigmata and so forth. The story of how her mother Mariah, the local churches and the media react to this phenomenon is somewhat interesting, but hardly requires a book of this length.
And the romantic side-story involving Mariah and the television atheist, Ian, is terrible. Can you say "wish-fulfillment fantasy"? I'm sure every middle class, newly-divorced woman fighting for custody of her child would love the ego boost of a rich, handsome single man falling madly in love with her for no apparent reason, but.... yeah right. It's unclear why he's even interested.
I've read two Picoult novels now, to give her a fair chance, but don't kid yourself: the unique-sounding plotlines are really just a cover for poorly written melodrama and even more poorly written romance. Unless this is your taste in guilty-pleasure reading, I'd recommend moving on to books of real quality.