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,  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.
The “who” in verse 5 refers back to the “us” in verse 3.
That means that those who have been born again through the resurrection of Jesus Christ are being guarded by God’s power through faith.
I haven’t gotten to the bottom of this, but it fascinates me that God preserves believers through their faith. Believers have the infinite might of God upholding their faith. Your faith will never die, because the power behind it is God’s power.
It’s another reason we shouldn’t put our faith in faith, but rather our faith should be in the God of our faith.