Yes, apostasy happens. Sometimes the catalyst is flagrant sin. The pain of conviction and repentance is refused, and the only alternative to it is wholesale rejection of Christ. But sometimes the catalyst is a thorn growing quietly in the heart, an indifference to the way of the Cross, a drifting that is not reversed by the knowledge of biblical warnings.

I can still recall the conversation although it took place more than three decades ago. A shocked friend asked, “Have you heard that Sarah is no longer a Christian?” What was so alarming to my friend was that Sarah had been one of the most influential, and apparently fruitful, members of her Inter-Varsity group. What would those who had been influenced by her witness to Christ say, or do? Would they be shaken to the core and now doubt their own Christian faith? After all, the person who had pointed them to Christ no longer trusted Him.

On occasion, we wonder if an individual really has been converted. And sometimes we have an inexplicable, ill-defined sense that something is missing. But we cannot read the heart. Even so, we hear of friends—whose faith we never doubted—turning away from Christ.

Apostasy is the old, vigorous word to describe this abandonment of Christ. The New Testament church was familiar with it. It was a major concern of the author of Hebrews. That is why he wrote the often-discussed words of Hebrews 6:4–6:

Those once enlightened, who have tasted the heavenly gift, become partakers of the Holy Spirit, tasted the good Word of God and the powers of the coming age—if they fall away cannot be renewed again to repentance.

Some in the early church thought that the phrase “cannot be renewed” meant that those who stumbled could not be received back into fellowship. But our author does not have the penitent in mind. Rather, he is thinking of those whose hardness of heart blocks the way to the Cross and proves irreversible.

It has been said that there is no more powerful or detailed description of the true Christian in the New Testament than in the words of Hebrews 6:4–6. That is surely a breathtaking statement in the light of what is said about the first readers a few verses later. The author is confident of something “better” in them—the very things that accompany salvation (6:9). The implication is that, however powerful the experiences described in 6:4–6 may be, these are not the definitive marks of a Christian. They may be present when genuine faith is absent. In fact, Hebrews is telling us that which is possible to experience without actually being a Christian.

Something must be missing therefore from this list of influences and experiences. What Hebrews has already said about an earlier generation brings it to light: “the gospel was preached … to them; but the word which they heard did not profit them, not being mixed with faith” (Heb. 4:2 NKJV). There was no real trust in Christ, the crucified, risen, and reigning Savior.

The truth and the power of the gospel were experienced. But “experience” in itself is not regeneration unless gospel grace penetrates into the heart. Hebrews 6:4–6makes no mention of the crucified One being trusted and sin being rejected. Rather, despite rich spiritual experiences, heart unbelief and rejection of Christ, crucifying Him ourselves, are grimly possible.

The solemn fact is that none of us can tell the difference between the beginning of backsliding and the beginning of apostasy. Both look the same. So what are the tell-tale signs of this sickness unto death? Are there early symptoms that might alert us to our spiritual danger?

Hebrews 6:8–12 suggests three things we should look out for:

First, we should look for the presence of “thorns and briars” (v. 8). Here Hebrews echoes the words of our Lord in the Parable of the Soils. In some soils (hearts) the good seed of the Word is planted and seems to take root. But in fact the soil is infested with weeds that strangle the fruit of the good seed. “The cares of this world, the deceitfulness of riches, and the desires for other things entering in choke the word, and it becomes unfruitful” (Mark 4:19 NKJV).

Second, we should look for the absence of “things that [always] accompany salvation” (v. 9). What are these “things”? They are, surely, the fruit of the Spirit (Gal. 5:22–24). Paul interestingly contrasts verbally the fruit of the Spirit with the works of the flesh. These marks of grace are the natural outcome of regeneration. Furthermore, the Cross has a central place in such a life, for “those who are Christ’s have crucified the flesh with its passions” (Gal. 5:24 NKJV).

The third thing is perhaps the most alarming: The failure to show “diligence” and a tendency to become “sluggish” (vv. 11–12). Earlier the writer had warned how easy it is just to “drift away” (Heb. 2:1). But this drifting happens slowly, and it often goes unnoticed.

Yes, apostasy happens. Sometimes the catalyst is flagrant sin. The pain of conviction and repentance is refused, and the only alternative to it is wholesale rejection of Christ. But sometimes the catalyst is a thorn growing quietly in the heart, an indifference to the way of the Cross, a drifting that is not reversed by the knowledge of biblical warnings.

So perhaps a personal health check is in order. And today would be the wisest time to do it.

This post was originally published in Tabletalk magazine. This article is used with permission.