Scientology does not address the concept of deities at most levels. There have been implications that at the very highest levels, there are discussions of various religious figures (including Jesus) that would be incompatible with traditional beliefs of such figures, but those teachings, even if they exist, are only available to a very few members of the Church of Scientology.
Just because we call something a religion doesn't mean it's contrary to every other religion. Plenty of religions can get along with other religions. It all depends upon the core beliefs of the religions in question.
Now, Scientology does teach reincarnation. That's how we end up with so many engrams dragging us down. Does Lewis believe in reincarnation? I have no idea. If she doesn't, then again there's no problem with Christianity. If she does, she has a rather liberal view of Christianity, although that certainly doesn't make her unique. I know Christians who believe that God will save everyone, regardless of their religion. That's not traditionally Christian either.