One of the great themes of the book of Hebrews is the need to persevere. You cannot read the book of Hebrews with its warnings and its exhortation and not come away with the author saying to them, as he really preaches to them, that they need to persevere; they need to keep going; they need to not turn back, but they need to press on in the Christian life.
The warnings function in the book of Hebrews to alert the Christian audience and the readers to say, “If I don’t persevere, if I take my eyes off Christ, if I do not continue to walk with him and look to him, given who he is in all of his splendor and glory — that he is the Lord of Glory, the Great High Priest who has come — given all of that, then outside of him there is no salvation. [Dr. Stephen J. Wellum]
The threats of judgment against the audience of Hebrews often trouble interpreters because they sound as if true believers can lose their salvation. For this reason, these portions of Hebrews have often been battlegrounds between Christians who hold one view or the other on this issue. Although time won’t allow us to discuss this theological matter in much depth here, it will still help to comment on two important aspects of this issue.
First, we must keep in mind that the book of Hebrews is not a technical systematic theology. By this we mean that, often, the Scriptures use terminology, even terminology about salvation, with more variety than Christian theologians and theological traditions. In fact, every branch of the church tends to use certain theological terms more narrowly than the various ways they’re used in Scripture. This practice is almost unavoidable if we hope to have theological systems that aren’t confusing. Yet, this approach is also dangerous because it’s easy to read our own narrow definitions of terms and expressions into a book like Hebrews. This danger is especially evident when it comes to understanding the way the author of Hebrews described those who become “apostate,” or those who fall away from Christ.
On the one side, it’s helpful to note that the author of Hebrews never described apostates as having been “justified.” In the New Testament, this term is consistently reserved for true believers. But on the other side, the author of Hebrews did use some terminology that Evangelicals often reserve only for true believers, even if the New Testament doesn’t. For instance, in Hebrews 6:4-6, the author warned:
Those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, who have tasted the goodness of the word of God and the powers of the coming age… can fall away.
The difficulty here is that many of us use these and similar expressions in our technical theological vocabulary to describe only true believers. In reality, similar descriptions are used in the New Testament for those who participate in what theologians often call the “visible church.” This is distinctly different from the “invisible church,” or the body of true believers. People of the visible church are those who are part of the church outwardly but not necessarily inwardly. This distinction within the church is similar to the way Romans 2:28, 29 distinguishes between those who were Jews only “outwardly” — phaneros in Greek — with outward, physical circumcision, and those who were Jews “inwardly” — kruptos in Greek — and circumcised in the heart.
Second, we should always remember that the threat of divine judgment for apostasy is not unique to Hebrews. For example, we find similar warnings in passages like 1 Corinthians 10:1-13 and 2 Peter 2:21, 22. On the whole, the New Testament teaches that those who have saving faith in Christ will endure to the end. But those who utterly reject Christ demonstrate that their faith was not saving faith. Rather, their faith was only what theologians often call “temporary” or “hypocritical faith.” As 1 John 2:19 explains about apostates:
If they had belonged to us, they would have remained with us; but their going showed that none of them belonged to us.
Anytime anyone turns away from the Christian faith, they show that they did not actually belong to the invisible church.