God saved you by His Grace when you believed. And you can’t take credit for this; it is a gift from God. Salvation is not a reward for the good things we have done, so none of us can boast about it.
Ephesians 2:8-9 (NLT)

This means that anyone who belongs to Christ has become a new person. The old life is gone; a new life has begun!
II Corinthians 5:17 (NLT)

I give My sheep eternal life. They will never die, and no one can take them out of My Hand. My Father is the One who gave them to Me, and He is greater than all. No one can steal My sheep out of His Hand.
John 10:28-29 (ERV)

These “against-Christ” people used to be members of our churches, but they never really belonged with us or else they would have stayed. When they left us it proved that they were not of us at all.
I John 2:19 (TLB)