I agree.
I'd say that your next statement is the answer to this question...
Again, I agree.
However, because God chose a person in Christ before the foundation of the world ( Ephesians 1:4-5 ) that choice is unerringly carried out in a person's lifetime ( 2 Peter 3:9 ) when God places one of His elect in front of the preaching of His word:
" For after that in the wisdom of God the world by wisdom knew not God, it pleased God by the foolishness of preaching to save them that believe." ( 1 Corinthians 1:21 ).
So, "point of belief" is when the Holy Spirit indwells the believer ( Ephesians 1:13 ) and seals them unto the day of redemption ( Ephesians 4:30 ).
Admittedly, I've had to re-think this over the years, and I actually agree that a person is not "in Christ", or actually in the body of Christ until the Spirit does His work and His elect are called in this life.
I see this when I read of Paul stating here:
" Salute Andronicus and Junia, my kinsmen, and my fellowprisoners, who are of note among the apostles, who also were in Christ before me." ( Romans 16:7).
As for their names being written in the Book of Life?
That is from the foundation of the world ( Revelation 17:8 ).
Christ's sheep have an inheritance prepared for them from the foundation of the world ( Matthew 25:34 ).
It was not prepared for anyone else but His sheep, His elect.
Christ was foreordained to come and offer Himself on the cross from the foundation of the world ( 1 Peter 1:20 ) for them and no one else ( Matthew 1:21, John 10:11 ).
Why does one believe?
Because they are Christ's sheep ( Matthew 13:10-11, John 6:37-44, John 6:65, John 8:43-47, John 17:2, Philippians 1:29 ).
Why does one not believe?
Because they are not "of" His sheep ( John 10:26 ).
Why does one reject the preaching of the cross and think that it is foolishness?
Because they are of "them that perish".
Why does one believe the preaching of the cross and to them it is the power of God?
Because they are saved ( 1 Corinthians 1:18 ).
The Gospel truly is the power of God to everyone that believes ( Romans 1:16 )...
But there is a reason that we have believed on Christ, and God's word answers it.
Therefore, one who is chosen in Him before the foundation of the world and chosen to salvation ( 2 Thessalonians 2:13-14 ), truly is the recipient of the greatest gift known to man:
An everlasting relationship with a God who loved them, even when they were dead in trespasses and sins ( Ephesians 2:1-10 ).