The issue is not whether grieving the Holy Spirit has consequences. Scripture plainly says it does. The issue is whether Ephesians 4:30 teaches that a sealed believer can become unsealed and lose eternal life. The verse does not say that.
Paul says, “And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption” ~Ephesians 4:30. The warning is real, but so is the statement attached to it: “sealed unto the day of redemption.” If the seal can fail before that day, then the verse does not mean what it says.
Yes, God chastens His children. Hebrews 12:6 says, “For whom the Lord loveth he chasteneth, and scourgeth every son whom he receiveth.” That is not “mere chastisement.” It is serious. But Hebrews does not say chastening means God stops being Father to His children. It says, “if ye be without chastisement, whereof all are partakers, then are ye bastards, and not sons” ~Hebrews 12:8. Chastening proves sonship. It does not cancel it.
The question about how long someone can grieve the Spirit and still receive eternal life is not answered by Scripture with a number of days, months, or years. Scripture does not give that measurement, so I will not invent one. But Scripture does say this: “My sheep hear my voice, and I know them, and they follow me” ~John 10:27. A person who permanently rejects Christ and continues in unbelief has no biblical right to claim he is one of Christ’s sheep.
But Jesus also said of His sheep, “And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand” ~John 10:28. He did not say, “They might never perish.” He said, “they shall never perish.”
You said, “our end of the deal.” But Scripture says salvation is not resting on man’s unstable hand. “Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ” ~Philippians 1:6. It also says believers “are kept by the power of God through faith unto salvation ready to be revealed in the last time” ~1 Peter 1:5.
That does not excuse sin. Paul says, “God forbid. How shall we, that are dead to sin, live any longer therein?” ~Romans 6:2. A true believer can stumble grievously, but Scripture does not describe him as someone comfortable living in rebellion. “Whosoever is born of God doth not commit sin; for his seed remaineth in him” ~1 John 3:9. John is not teaching sinless perfection, because he already said, “If we say that we have no sin, we deceive ourselves” ~1 John 1:8. He is speaking of a settled practice of sin as a life pattern.
As for falling away, Scripture does speak of apostasy. But 1 John 2:19 explains the kind of departure that proves the person was never truly of Christ: “They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us.”
So I reject cheap “once saved, always saved” if it means a rebel can live for sin and still claim assurance. But I also reject the idea that Christ loses His sheep. Scripture teaches both: false professors fall away, and Christ keeps His own.
Matthew 7:21-23 “Not everyone who says to Me, ‘Lord, Lord,’ will enter the kingdom of heaven, but he who does the will of My Father who is in heaven will enter. 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 [a]miracles?’ And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness.”
2nd Corinthians 5:10: For we must all appear before the judgment seat of Christ, that each one may be recompensed for his deeds in the body, according to what he has done, whether good or bad..
Matthew 18:9 And if your eye causes you to sin, pluck it out and cast it from you. It is better for you to enter into life with one eye, rather than having two eyes, to be cast into hell fire.
Philippians 2:12 So then, my beloved, just as you have always obeyed, not as in my presence only, but now much more in my absence, work out your salvation with fear and trembling;
1st Corinthians 6:9-10 “Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived; neither the sexually immoral, nor idolaters, nor adulterers, nor homosexuals, nor thieves, nor the greedy, nor those habitually drunk, nor verbal abusers, nor swindlers, will inherit the kingdom of God”
Galatians 5:19-21 Now the deeds of the flesh are evident, which are: sexual immorality, impurity, indecent behavior, idolatry, witchcraft, hostilities, strife, jealousy, outbursts of anger, selfish ambition, dissensions, factions, envy, drunkenness, carousing, and things like these, of which I forewarn you, just as I have forewarned you, that those who practice such things will not inherit the kingdom of God.
Ephesians 5:3-5 But among you there must not be even a hint of sexual immorality, or of any kind of impurity, or of greed, because these are improper for God’s holy people. Nor should there be obscenity, foolish talk or coarse joking, which are out of place, but rather thanksgiving. For of this you can be sure: No immoral, impure or greedy person—such a person is an idolater—has any inheritance in the kingdom of Christ and of God.
John 5:28-29 Do not marvel at this; for an hour is coming, in which all who are in the tombs will hear His voice, and will come forth; those who did the good deeds to a resurrection of life, those who committed the evil deeds to a resurrection of judgment.
Romans 2:5-6 But because of your stubbornness and unrepentant heart you are storing up wrath for yourself in the day of wrath and revelation of the righteous judgment of God, who will render to each person according to his deeds: