Okay. So whether adopted or begotten.
What does it mean to be a brother of Christ?
You should be careful though. In your attempt to escape the eminent conclusion, you're on the cusp of saying that a man
musn't be born again. We who are saved are "born of God," "begotten of God," and "partakers of the divine nature."
1 John 4:7 - Beloved, let us love one another: for love is of God; and every one that loveth is born of God, and knoweth God.
1 John 5:1 - Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth him that begat loveth him also that is begotten of him.
1 John 5:4 - For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith.
2 Peter 1:4 KJV - Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust.
None of this was true of Adam, even in his innocence. Neither is it true of the angels. It is true of Christ.
Redemption doesn't merely restore us to mankind's first estate, a little lower than the angels. It is much more glorious than that.
Romans 8:29 BBE -
Because those of whom he had knowledge before they came into existence, were marked out by him to be made like his Son, so that he might be the first among a band of brothers:
Romans 8:29 NLT - For God knew his people in advance, and he chose them to become like his Son, so that his Son would be the firstborn among many brothers and sisters.
1 John 3:2 KJV - Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is.
I think it's abudantly clear that those who were predestined to be conformed to the image of His Son, are predestined to salvation.