Well, I have found anyone who has a certified religious belief is not going to give it up easily. Mormons will dance around their "Native Americans are descended from the lost tribes of Israel" Book of the Mormon teaching , rather than admit Joseph Smith was wrong, then admit that the Book of Mormon was wrong, then admit their religion is just the invention of a 19th century con artist. It is rather hard to debate a JW in the flesh, I have found.
I've tried and they always cut it off- "this is not a productive conversation", they say- like it's all my fault they have to leave.