Hebrews 6: 4 For it is impossible to restore again to repentance those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit,  and have tasted the goodness of the word of God and the powers of the age to come,  if they then fall away, since they are crucifying once again the Son of God to their own harm and holding him up to contempt.  For land that has drunk the rain that often falls on it, and produces a crop useful to those for whose sake it is cultivated, receives a blessing from God.  But if it bears thorns and thistles, it is worthless and near to being cursed, and its end is to be burned.
You know them. They may be your relatives, your children, your parents. Perhaps your pastor or the person who first introduced you to the Gospel. And then there are the famous; the television evangelists, the scholars who had devoted their lives to the study of the Scriptures, missionaries who had sacrificed everything for the sake of getting the Gospel into the hearts and minds of people who had never heard it. And now they no longer live for Christ. Their doubts have taken over and won. Their secret sins were finally exposed, either voluntarily or otherwise, and they have given up trying. They no longer believe. They no longer care. They no longer call themselves Christian.
There have always been such events and there will always be those people who give up on the faith they were professing. But in the face of such realities how can anyone claim that once a person is saved they can never be not saved? How can we say that there is no such thing as a “former believer”? This section of Hebrews deals with people who forsake the faith and turn away from it. And the debate rages between those who claim that salvation can never be lost and those who say it can. This text is one of the strongest for those who maintain that a person can turn away from the God who saved him, even though God did not give up on him. Personally, if I believed that salvation could be lost, this is the last text I would want to have to deal with.
A couples of points: 1) If this text says that salvation can be lost then it also says that it can never be found again. “For it is impossible, in the case of those who have once been enlightened … and then have fallen away, to restore them again to repentance …”. Once a person forsakes the faith he will never be convinced to repent. If this text teaches that there is such a thing as a former believer it also teaches that there is no such thing as a “believer again”. Might as well bar the church door to them and tell them to sleep in on Sunday mornings. Tell them to go live like the devil. It’s him they are heading for anyway. All those children who were baptized at age eight and then discovered the pleasures of adolescence and now want nothing to do with the faith; just stop praying for them. Stop telling them to “come back”. They can’t.
But the text does not say that they were part of the kingdom of God. It does not say that they were truly converted. It does not say that they were saved. In fact, it says just the opposite. Whatever verses 4 and 5 mean we know that none of the things mentioned there refer to real salvation in the heart of these apostates. Don’t stop reading at verse 6. Read at least as far as verse 9. Verse 9 clears things up.
2) Second point then – read the entire context of a passage of Scripture before you make a conclusion regarding its meaning. Verse 9 says that the writer to the Hebrews is convinced that the tragedy referred to in verses 4-8 is not the case in the people he is writing. He is convinced of better things for them – things that belong to salvation. In other words, the things he refers to in verses 4-8 do not belong to salvation. Falling away (verse 6) does not belong to salvation. Bearing thorns and thistles, being worthless, being near to being cursed and in the end being burned, (verse 8 ) do not belong to salvation.
Real Christians will bear real fruit. They will not fall away. They will not do that which is near to being cursed and they will not do anything that is worthless. This whole section is nothing more than what Jesus taught about a good tree bearing good fruit, and real disciples bearing their cross and counting the cost. Real Christians will do it. False believers will pull back. They are the seed that falls on rocky soil that springs up right away but cannot last because it has no root. Real believers have roots that hook right into the keeping and life changing power of the triune God.
So where does that leave you? Is your faith a mental assent that cannot handle the challenges of a life lived for Christ? Is it no more than fair weather Christianity that will give up when the temperature rises? Is it a faith that works (James 2:14-17)? Real faith in the real Saviour will be accompanied by a real power to persevere, and repent when it has sinned. Be satisfied with nothing less for anything else is not real at all.