The Meaning of the Woman and the Beast
7 But the angel said to me, “Why did you marvel? I will tell you the mystery of the woman and of the beast that carries her, which has the seven heads and the ten horns.
8 The beast that you saw was, and is not, and will ascend out of the bottomless pit and go to perdition.
And those who dwell on the earth will marvel, whose names are not written in the Book of Life from the foundation of the world, when they see the beast that was, and is not, and yet is.
v17 implies our names were written in the Book of Life or not written in the Book of Life before the foundation of the world, First names are written or not written, then the world created.
Revelations 17 here agrees with Ephesians 1, with our names meaning our identity chosen in Him before God created I suppose any other thing.
3 Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ, 4 just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love, 5 having predestined us to adoption as sons by Jesus Christ to Himself, according to the good pleasure of His will, 6 to the praise of the glory of His grace, by which He made us accepted in the Beloved.
This Ephesians passage is referring to genuine real persons, not the church.
So before this in Gen 1, our names were written in Heaven, what better evidence exists that salvation can not be lost, if our names were written in the Book of Life before all things were made?
Genesis 1New King James Version (NKJV)
The History of Creation
1 In the beginning God created the heavens and the earth.
2 The earth was without form, and void; and darkness was on the face of the deep. And the Spirit of God was hovering over the face of the waters.
So prior to this here in Genesis 1, we have proof God did something.