Well, as I said, (Rev. 22:17-19) pertains to anyone, everyone, and whosoever. That means, at the least, not just the saved. So, how can those that are not saved have their part taken out of the 'book of life', if he didn't have a part.
And we are never told that our names are added to that book when we believe. And we are not told when they were written in either. Just that they are written.
What we do know is God will never blot out the believer from the 'book of life'. (Rev. 3:5), (1 John 5:5). Whether (Rev. 22:17-19) is speaking to the same thing, is questionable as it doesn't say ones name is blotted out. It says He will take away His part.
And remember, one cannot lose their salvation because of a sin. Most especially, one sin. I believe there is more here than I understand. And much more than you understand. We didn't get saved by not sinning. We got saved by belief.
Stranger