Authentically Born Again Believers Do Not Fall Away

Those who "go away" from God were never His in the first place. They only had an appearance of godliness, and when it became too tiresome to live for God in their own effort, they fell away.

 
1 John 2:19
"19 They went out from us, but they were not really of us; for if they had been of us, they would have remained with us; but they went out, so that it would be evident that they all are not of us."

When we have been changed by Christ into a new creation, the old things are gone and we have become brand new. When Christ changes someone, they do not want to change back; they are eternally saved.

God does not throw away the believer who sins, but He does discipline them to come back to obedience.

 
Job 5:17
Blessed indeed is the man whom God corrects; so do not despise the discipline of the Almighty.

2 Corinthians 13:5 "5 Examine yourselves to see whether you are in the faith; test yourselves. Can’t you see for yourselves that Jesus Christ is in you— unless you actually fail the test? "

Many people who decided to join the Christian club to feel safe and even good about themselves were never changed by Christ because they didn't put their trust in Him, they trusted in themselves in their own strength to do what they knew was right, but their hearts were never changed because they wanted to do it themselves. These are the people who often misinterpret scripture because they are not seeking Christ they are using the scripture to justify their own thinking.

 
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.’"

It does not say I knew you and you changed your mind and walked away, it says "I NEVER KNEW YOU. "Christ did not do the changing so those who attempted to change themselves, proud of how good they thought they were, had no relationship with Christ.

 
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.” 7 Endure suffering as discipline; God is treating you as sons. For what son is not disciplined by his father?…"