The author of Hebrews has issued a call to Christian maturity, provided a description of Christian maturity, and informed his readers of the foundation that is necessary for Christian maturity. Each of these exhortations to maturity were positive, explaining what Christians ought to be, do, and have, in order to gain spiritual maturity. In 6:4-8, the author moves on to a negative exhortation, explaining the consequences of failing to grow into mature Christians.
A healthy child never stops growing. If a three-year-old doesn’t grow at all for a period of a few months, her parents would be right to worry. Their concern, however, would not centre on the possibility that their daughter might not grow past three-foot-one, but that the lack of growth is a symptom of a very serious underlying health problem.
Similarly, a Christian who stops growing and maturing spiritually is not just “missing out” on the benefits of spiritual growth. Rather, his lack of spiritual growth is an alarming symptom of a very fundamental spiritual malady. If a Christian is not growing, the author says, it is likely that he is not really a Christian at all.
His exhortation is in three parts. First, he shows how far an individual may progress in the Christian life, before her profession of faith is ultimately proven false. She may be “enlightened” to Christian truth, and brought to “taste” or experience for herself “the heavenly gift” of salvation. She may appear to be a genuine “partaker” of the spiritual life produced by the Holy Spirit. She may have “tasted the good word of God, and the powers of the world to come,” finding real delight in the Scriptures and in thoughts of eternal life.
Second, he shows how serious a sin it is to fall away from the faith. To fall away, he says, is to “crucify the Son of God afresh, and put him to an open shame.” In other words, the apostatizing (falling-away) Christian is declaring his agreement with those who killed the Lord Jesus. Moreover, he is shaming the name of Christ, because his faith is exposed to all as a sham.
Third, he shows how difficult it is for an apostate to be restored to faith in Christ. It is more difficult for an ex-Christian to be saved than a non-Christian. An ex-Christian has a bitterness against the truth, a series of broken relationships with Christians, and an ego that is now doubly sensitive to the humility of true repentance. It is only “impossible” for him to be saved in the sense that it is “impossible” for anyone to be saved apart from God’s grace and power. God certainly can save an apostate, and has done so on occasion, but this is the exception, not the rule.
The practical implication of the author’s warning is that we must never rest content with our current spiritual condition. A real Christian is always a growing Christian, and a Christian who stops growing is likely not a Christian at all. No matter what stage of Christian life we are at, or what degree of knowledge, service, or experience we have attained, we are never done pressing onward towards the goal of full Christian maturity.
None of this is to say that a true Christian can lose his salvation. The false profession that ends in apostasy may show all the features mentioned in vv.4-5, but these are not the sum of true faith. Those who are truly saved will always persevere in their faith in Christ to the end; yet it is still true that only those who persevere in their faith, seeking constantly to grow in maturity, are actually saved and will ultimately be saved.