When Christ changes someone into a new creation it is His work and not ours. Nothing we do can save us or lose us, it is Christ Who seals us.
2 Corinthians 1:22; Ephesians 1:13; 4:30, is the mark of identification that the believer is truly God's own and is kept forever by the power of God.
Ephesians 2:10
"10 For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them."
If we could do anything to keep our own salvation then salvation would depend on us entirely. Christ is the only One Who can change a person into an entirely new person.
Those who walk away after claiming to be a Christian were attempting to save themselves and were never born again.
Matthew 7:21-23
I Never Knew You
21 “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. 22 On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ 23 And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’"
Notice the word; "never", God said He never knew the one who claimed to be a Christian but walked away.
God also says, no child of God keeps on sinning, in other words if we sin it is giving into the flesh and we repent to be cleansed to grow in holiness.
1 John 1:9
"9 If we confess our sins, He is faithful and righteous, so that He will forgive us our sins and cleanse us from all unrighteousness."
Those who are born again battle with the flesh but resist the sin, if they fall they have an advocate with the Father. The one who says they are Christian but has no staying power was never born again. It is Christ Who keeps us, not our own will.
1 John 3:9 ""No one born of God makes a practice of sinning, for God's seed abides in him; and he cannot keep on sinning, because he has been born of God"
1 John 2:1-2 "1 My little children, I am writing these things to you so that you will not sin. But if anyone does sin, we have an advocate before the Father— Jesus Christ, the Righteous One. 2 He Himself is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world.…"
Those who fight to defend their sin or walk away were never born again in the first place, they were pretenders.
The five virgins did not have the Holy Spirit and weren't saved. Those who had enough oil, that is the Holy Spirit were those who never turned back.
The five virgins who walked away knew of Christ but did not heave His Holy Spirit. They never belonged to Him. The five foolish virgins knew of Christ but never placed their trust in HIm. The five wise virgins were indwelt with the Holy Spirit, belonged to Christ and would not be turned a way based on their own good deeds but based on the righteousness of Christ.
Luk 13:23-27 Someone asked him, "Lord, are only a few people going to be saved?" He said to them, (24) Make every effort to enter through the narrow door, because many, I tell you, will try to enter and will not be able to. (25) Once the owner of the house gets up and closes the door, you will stand outside knocking and pleading, 'Sir, open the door for us.' "But he will answer, 'I don't know you or where you come from.' (26) Then you will say, 'We ate and drank with you, and you taught in our streets.' (27) But he will reply, 'I don't know you or where you come from. Away from me, all you evildoers!'"
Many people know of Christ and even believe He exists but have no desire to be changed by Him, they want to walk their own path believing in themselves.
Proverbs 28:26
"26 Those who trust in themselves are fools, but those who walk in wisdom are kept safe."
Our salvation is not dependent on how good we are, it is dependent on the work of Christ on the cross. In response to our confession that we have sinned and cannot save ourselves, along with our desire to be changed by Him into a new creation, He does all the work on our behalf. He saves us, He cleanses us over our lifetime as we grow in holiness and He advocates for us before the Father.
If we fail in the flesh Christ disciplines us to bring us back to obedience and advocates to the Father on our behalf.
Hebrews 12:5-7 "…5 And you have forgotten the exhortation that addresses you as sons: “My son, do not take lightly the discipline of the Lord, and do not lose heart when He rebukes you. 6 For the Lord disciplines the one He loves, and He chastises every son He receives.” 7Endure suffering as discipline; God is treating you as sons. For what son is not disciplined by his father?"
No one will be saved who depends on their own ability to be good, only those who have fully trusted Christ and believe Him when He says He already did the work to pay for our sin on the cross.
Trusting Christ is not a work, it is a heart belief in His work on the cross and a desire to be changed by Him. When He does this He changes the WAY we think entirely so that we no longer love the sin we used to obey as slaves to it. After He changes us we love His righteousness. When we fail in the flesh we hate it and confess it to be cleansed.
1 John 1:9 "
"9 If we confess our sins, He is faithful and righteous, so that He will forgive us our sins and cleanse us from all unrighteousness."
Only those who have been changed by Christ after they have repented will have His righteousness accounted to them and will battle sin in the flesh to grow in holiness over their lifetime until He takes us home.
Ephesians 1:14: "The Spirit is the guarantee of our inheritance until the redemption of God's own possession, to the praise of His glory".
Our Guarantee is the Holy Spirit, It is God's seal on us and a promise to us that we will never be lost again. There will be many pretenders who claim to be Christians but have never trusted in Christ, they wanted all His blessings and perks but they didn't want Him.
Ephesians 1:13-14
13 In Him, you also, after listening to the message of truth, the gospel of your salvation—having also believed, you were sealed in Him with the Holy Spirit of the promise, 14 who is a first installment of our inheritance, in regard to the redemption of God’s own possession, to the praise of His glory."