When she wrote the porn she wasn't a Christian. She had rejected religion and openly mocked it. Then, after writing the vampire novels and other novels (including the porn) she turned back to religion and started writing about what Jesus was like as child.
As far as I know she hasn't disavowed her earlier work, but her later books aren't selling at the same level. Last year I stumbled over a radio interview with her where she talked about the process of rediscovering her Catholic faith and how hard it was for her husband (a "devote atheist") to re-marry in a church (otherwise they would be living in sin).
Technically she never wrote porn or erotica under her own name - she had two pen names. One for the porn (the Beauty series) and one for the Erotica (Exit to Eden and Belinda).
Yes, there was a time when I was really into her vampire series (before being disappointed by the later books) and I tracked down everything she wrote. The book about the castrati was a bit disturbing, but nothing compared to Belinda...
See
http://en.wikipedia.org/wiki/Belinda_%28Rice_novel%29 for details of why Belinda was disturbing. Rice delved into that subject matter with the same passion (and perhaps the same flaws) as she did with Exit to Eden.
Oh, and it's been a while but I don't think anything On Topic happened in Belinda. I'm sure I would have remembered if there had been a spanking, caning, or whatever in that book.
Goodgulf