The born again experience is instantaneous, done by God Himself and irreversible. The salvation of the soul is also done by God, but it is conditional, dependent on our willingness to be changed. God does His part and we must respond.
Rev 21:27 And there shall in no wise enter into it any thing that defileth, neither whatsoever worketh abomination, or maketh a lie: but they which are written in the Lamb's book of life.
The lambs book of life is important.
If your name is not in there you are not saved.
A person’s name is recorded in the book of life when they manifest repentance for sin, exercise faith in Jesus Christ, and choose to serve God. True faith.
While our names are entered when we first believe, the Scriptures warn that it is possible for a name to be blotted out if a person turns back to a life of sin or fails to overcome. We are currently living in a time where the records of heaven are being examined to see who has remained faithful to the end.
Rev 3:5 He that overcometh, the same shall be clothed in white raiment; and I will not blot out his name out of the book of life, but I will confess his name before my Father, and before his angels.
Exo 32:33 And the LORD said unto Moses, Whosoever hath sinned against me, him will I blot out of my book.
Eze 18:24 But when the righteous turneth away from his righteousness, and committeth iniquity, .....and in his sin that he hath sinned, in them shall he die.
Dan 12:1 And at that time shall Michael stand up, the great prince which standeth for the children of thy people: and there shall be a time of trouble, such as never was since there was a nation even to that same time: and at that time thy people shall be delivered, every one that shall be found written in the book.
Rev 20:15 And whosoever was not found written in the book of life was cast into the lake of fire.
Knowing that your name can be blotted out or removed from the book of life is important. You can loss salvation.