Well, I "lost" also a biblestudy before to some thing very similar to JW's.
Anyway, it helped me to realize that I could not find any real reason for him to follow us and not them. So, it created some doubt at that time.
If you look very close at the bible you probably get something like the JW's. (some details different maybe)
All religion is dangerous, so how more different ones the better, as that will make them fall apart sooner