The book of Hebrews says it is impossible for an apostate to be restored. How does this square with
4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,
5 And have tasted the good word of God, and the powers of the world to come,
6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
There are two valid ways of looking at these verses:
One interpretation holds that this passage is written not about Christians but about unbelievers who are convinced of the basic truths of the gospel but who have not placed their faith in Jesus Christ as Savior. They are intellectually persuaded but spiritually uncommitted.
According to this interpretation, the phrase “once enlightened” (verse 4) refers to some level of instruction in biblical truth. However, understanding the words of scripture is not the same as being regenerated by the Holy Spirit.
9 That was the true Light, which lighteth every man that cometh into the world.
The “true Light,” giving light “to every man”; does not mean the light of salvation, because not every man is saved. Through God’s sovereign power, every man has enough light to be held responsible.
This light either leads to the complete acceptance of Jesus Christ or produces condemnation in those who reject such light. The people described in Hebrews 6:4-6 are of the latter group—unbelievers who have been exposed to God’s redemptive truth and perhaps have made a profession of faith, but have not exercised genuine saving faith.
This interpretation also sees the phrase “tasted the heavenly gift” as referring to a momentary experience, akin to Jesus’ “tasting” death.
9 But we see Jesus, who was made a little lower than the angels for the suffering of death, crowned with glory and honour; that he by the grace of God should taste death for every man.
This brief experience with the heavenly gift is not seen as equivalent to salvation; rather, it is likened to the second and third soils in Jesus’ parable (Matthew 13:3-23), which describes people who receive the truth of the gospel but are not truly saved.
Finally, this interpretation sees the “falling away” (Hebrews 6:6) as a reference to those who have tasted the truth but, not having come all the way to faith, fall away from even the revelation they have been given. The tasting of truth is not enough to keep them from falling away from it. They must come all the way to Christ in complete repentance and faith; otherwise, they in effect re-crucify Christ and treat Him contemptuously.
Those who sin against Christ in such a way have no hope of restoration or forgiveness because they reject Him with full knowledge and conscious experience. They have concluded that Jesus should have been crucified, and they stand with His enemies. It is impossible to renew such to repentance.
The other interpretation holds that this passage is written about Christians, and that the phrases “partakers of the Holy Ghost,” “enlightened,” and “tasted of the heavenly gift” are all descriptions of true believers.
According to this interpretation, the key word in the passage is if (verse 6). The writer of Hebrews is setting up a hypothetical statement: “IF a Christian were to fall away . . .” The point being made is that it would be impossible (IF a Christian falls away) to renew salvation.
26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
That’s because Christ died once for sin and if His sacrifice is insufficient, then there’s no hope at all.
28 So Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation.
The passage, therefore, presents an argument based on a false premise (that a true Christian can fall away) and follows it to its senseless conclusion (that Jesus would have to be sacrificed again and again). The absurdity of the conclusion points up the impossibility of the original assumption. This reasoning is called “reductio ad absurdum”, in which a premise is disproved by showing that it logically leads to an absurdity.
Both of these interpretations support the security of the believer in Christ. The first interpretation presents unbelievers rejecting Christ and thereby losing their chance of salvation; the second interpretation presents the very idea of believers losing salvation as impossible.
Many scriptures make it abundantly clear that salvation is eternal (John 10:27-29; Romans 8:34–39; Philippians 1:6; 1 Peter 1:4-5), and Hebrews 6:4-6 confirms that doctrine.
27 My sheep hear my voice, and I know them, and they follow me:
28 And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand.
29 My Father, which gave them me, is greater than all; and no man is able to pluck them out of my Father's hand
34 Who is he that condemneth? It is Christ that died, yea rather, that is risen again, who is even at the right hand of God, who also maketh intercession for us.
35 Who shall separate us from the love of Christ? shall tribulation, or distress, or persecution, or famine, or nakedness, or peril, or sword?
36 As it is written, For thy sake we are killed all the day long; we are accounted as sheep for the slaughter.
37 Nay, in all these things we are more than conquerors through him that loved us.
38 For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come,
39 Nor height, nor depth, nor any other creature, shall be able to separate us from the love of God, which is in Christ Jesus our Lord.
6 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:
1 Peter 1:2-7
2 Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you, and peace, be multiplied.
3 Blessed be the God and Father of our Lord Jesus Christ, which according to his abundant mercy hath begotten us again unto a lively hope by the resurrection of Jesus Christ from the dead,
4 To an inheritance incorruptible, and undefiled, and that fadeth not away, reserved in heaven for you,
5 Who are kept by the power of God through faith unto salvation ready to be revealed in the last time.
6 Wherein ye greatly rejoice, though now for a season, if need be, ye are in heaviness through manifold temptations:
7 That the trial of your faith, being much more precious than of gold that perisheth, though it be tried with fire, might be found unto praise and honour and glory at the appearing of Jesus Christ:
Finally, you can NEVER truly lose your salvation, if truly accepted Christ in your heart, if that is true it will manifest in the way you live your life and interact with people. The prodigal son is always his fathers son, no matter his behavior. The key is that you must be your fathers son…