Hello BC
On two of your verses I prefer to use the NAS.
2 Corinthians 7:8-10
8. For though I caused you sorrow by my letter, I do not regret it; though I did regret it-- [for] I see that that letter caused you sorrow, though only for a while--
9. I now rejoice, not that you were made sorrowful, but that you were made sorrowful to [the point of] repentance; for you were made sorrowful according to [the will of] God, so that you might not suffer loss in anything through us.
10. For the sorrow that is according to [the will] [of] God produces a repentance without regret, [leading] to salvation, but the sorrow of the world produces death.
2 Corinthians 12:21
21. I am afraid that when I come again my God may humiliate me before you, and I may mourn over many of those who have sinned in the past and not repented of the impurity, immorality and sensuality which they have practiced.
A lot of people will call themselves Christians but they have never repented from their ways. Repentance requires a change of attitude and lifestyle. Everyone that has been saved and lived any decent length of time has sinned again, it is the nature of man. The Christian will not embrace his shortcomings, he will always try to improve his relationship with his Creator. For those people who call themselves Christians and continue to live their old way of life and never actually enter into repentance Christ had this to say about them:
Matthew 7:22-23 NAS
22. "Many will say to Me on that day, 'Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many miracles?'
23. "And then I will declare to them, '
I never knew you; DEPART FROM ME, YOU WHO PRACTICE LAWLESSNESS.'
I highlighted where he said "I never knew you", because it shows that these people never were saved, they never knew Christ and Christ never knew them because they never really did repent and turn from their old ways.
I believe strongly that once you are saved you are always saved, it is a work of our Lord Jesus Christ and it cannot be reversed by man or Satan. A true Christian will always try to be close as he can to his Lord, always seeking his favor and forgiveness. This is the new nature of the Christian and his rebirth.
Proof:
John 10:28-29
28. and I give eternal life to them, and they will never perish; and no one will snatch them out of My hand.
29. "My Father, who has given [them] to Me, is greater than all; and no one is able to snatch [them] out of the Father's hand.
John 3:16
16. "For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life.
Romans 8:38-39
38. For I am convinced that neither death, nor life, nor angels, nor principalities, nor things present, nor things to come, nor powers,
39. nor height, nor depth, nor any other created thing, will be able to separate us from the love of God, which is in Christ Jesus our Lord.
Hebrews 10:26
26. For if we go on sinning willfully after receiving the knowledge of the truth, there no longer remains a sacrifice for sins,
Hebrews 6:4-6
4. For in the case of those who have once been enlightened and have tasted of the heavenly gift and have been made partakers of the Holy Spirit,
5. and have tasted the good word of God and the powers of the age to come,
6. and [then] have fallen away, it is impossible to renew them again to repentance, since they again crucify to themselves the Son of God and put Him to open shame.
