Jesus said those He gives eternal life will never perish in John 10:28. So your conclusion is in direct conflict with what Jesus said.Yes, the one who is not in union with Christ will spend eternity apart from Him.
I wouldn't expect to.You will never find one passage that states eternal life is something you possess without being in union with Christ.
Also, you will never find any passage that states that one who has been given eternal life will perish.
The few verses about "leaving" or "severed" etc would be in direct conflict with what Jesus said, IF they meant loss of union with Christ.When a person leaves Christ, they leave the only eternal life there is.
Is that a position one would be comfortable with?
Not me.