Blessed be the God and Father of our Lord Jesus Christ! According to his great mercy, he has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, (1 Peter 1:3 ESV)
It was according to God's Mercy that he caused us to be born again. It wasn't anything we deserved or did. We didn't cause it ourselves it was the work of God. Now since it was God that caused us to be born again and he did the work then guess what, it lasts forever!
to an inheritance that is imperishable, undefiled, and unfading, kept in heaven for you, who by God's power are being guarded through faith for a salvation ready to be revealed in the last time. (1 Peter 1:4-5 ESV)
The inheritance is imperishable, which means it cannot go away it will last forever. Our salvation is being guarded by God. That is powerful stuff!
Since God caused our Salvation he will make sure it lasts forever!
All Glory to God!