Once saved BY GOD and Faith implanted by God, and yes, He doesn't give up on His children which, He has birthed.
It is God who has brought folks like us out of Spiritual Deadness and Made us alive in Christ (Ephesians 2:5). We did not cause ourselves to be alive, He did. We did not raise ourselves from being Dead in Trespasses and Sins, He did.
So once Saved by God is key to the discussion here, and not believing we Saved ourselves.
God implanted Faith in Folks like us, we didn't do it to ourselves. Romans 12:3 says "For by the grace given to me I say to everyone among you not to think of himself more highly than he ought to think, but to think with sober judgment, each according to the measure of faith that God has assigned.
God implanted Faith in folks like us even a measure by His grace, and we did not do this ourselves.
The Faith Given indicates Eternal Life: The Lord Jesus Christ says "HE WHO BELIEVES HAS EVERLASTING LIFE" John 6:47
Why do we not Believe Him?? Why do we believe that we can take ourselves out of God's hand and are more powerful than He is?? "My Father, who gave them to me, is greater than all; and no man is able to pluck them out of my Father's hand" John 10:29 Why do people believe they are more powerful than God?
It is He that has Birthed folks like us who believe upon Christ Alone for salvation. We did not Birth ourselves. John 1:12 "born 'not of the will of man, but of God' Says the Apostle whom Jesus Loved (the Apostle John).
Why do we believe we birthed ourselves?? Why do we believe we can loose the Salvation authored, given freely to us, and His raising us up from being Dead in Tresspasses and Sins? Why?
Yes, Once Saved by God and His raising us up from Spiritual Deadness is the key. Yes, "being confident of this, that he who began a good work in you will carry it on to completion until the day of Christ Jesus" Philippians 1:6, Always Saved.