First off, this book goes some dark places. Because it's enevitable that it's going to be compared to 50 Shades of Grey (and probably Silvia Day's Crossfire series), fuck it, I'll go there. 50 Shades wants to pretend it gives Christian a dark and tortured past. The Saint looks at 50 Shades and laughs it's ass off.
And yeah, I get why there's bible verses and some religion involved. The main love interest IS a priest (and a sadist), so that makes sense, but it's just super weird for me.
The Saint is the 5th Original Sinners book (the first of "The White Years"), and while it "takes place" after 4 books, 90% of the book is the telling of Eleanor/Nora's introduction to Soren, Kingsley, and BDSM... so reading it first basically means you're just reading backstory and it all works out. Actually, it looks like most of "The White Years" books (5-8)take place before "The Red Years" (books 1-4).
I do want to give Reisz for probably one of the few erotic romance books I've read that actually uses "clitoris," "vagina," "penis," and "erection." There's one or two cases of more flowery/euphemistic language, but very little... and it was kind of awesome to read a book that uses proper words and does it well.
But back to the first paragraph. things starts out with sexual tension between a 15 year-old and a 28 year-old. It's a BDSM novel, so expect all sorts of things there (if you don't like bondage and sadism, don't read this book). There is also mention of rape, abuse, and incest - not as active parts of the story, but as spoken confession/revelation.