While Hebrews seems to very plainly teach that Christians might fall away, what about Paul? Those who teach perseverance of the saints (POTS) often rely on his teachings.
However, James D. G. Dunn points out that there are passages in Paul that seem to contradict POTS, such as —
(Phi 3:12-14 ESV) Not that I have already obtained this or am already perfect, but I press on to make it my own, because Christ Jesus has made me his own. 13 Brothers, I do not consider that I have made it my own. But one thing I do: forgetting what lies behind and straining forward to what lies ahead, 14 I press on toward the goal for the prize of the upward call of God in Christ Jesus.
It does seem clear that Paul considers final salvation as not yet attained. Rather, he must “press on” while “straining forward.” (And like Dunn, I part company with NT Wright at this point.)
Similarly, Paul also writes,
(1Co 9:24-27 ESV) Do you not know that in a race all the runners run, but only one receives the prize? So run that you may obtain it. 25 Every athlete exercises self-control in all things. They do it to receive a perishable wreath, but we an imperishable. 26 So I do not run aimlessly; I do not box as one beating the air. 27 But I discipline my body and keep it under control, lest after preaching to others I myself should be disqualified.
Paul certainly seems to consider the risk of disqualification very real.
But does Paul actually mean that one can fail to obtain the prize? Some would say no, but usually because of a prior theological commitment, not because of what the text itself says. While it is true that in 10:13, after the severe warnings spelled out in vv. 1–12, he once again puts his confidence in God to “keep them,” it would be sheer folly to suggest thereby that the warnings are not real. Paul keeps warning and assurance in tension.
Simultaneously he exhorts and, by this and the following examples, warns the Corinthians of their imminent danger if they do not exercise “self-control” in the matter of idolatry; yet, as always (cf. on 5:8 and 6:11), he reminds them of their security in the prior activity of God, who has committed himself to them in Christ Jesus.
Gordon D. Fee, The First Epistle to the Corinthians, The New International Commentary on the New Testament, (Grand Rapids, MI: Wm. B. Eerdmans Publishing Co., 1987), 440.
Fee is right, I believe. Paul teaches both assurance and warning, comfort and caution. So does the author of Hebrew. After all, both are true. We’ll delve more deeply into the tension in a few posts, but for now, the key thought is that both are true. We do indeed need to press on, straining forward, being careful not to be disqualified. We can fall away. But we’re also promised confidence and assurance (Heb. 3:6, 14; 4:16; 6:11; 10:19, 22, 35; 11:1; 13:6).
But it’s not as easy as every sin or every doctrinal error damns. Again, the OT gives us the template. God is patient. God does not damn as soon as Israel makes its first mistake. But there does come a point at which God gives up even on his elect people — but that point normally doesn’t come quickly.
On the other hand, the OT is clear that rebellion is a deadly, fearful sin. Consider —
(Heb 12:15 ESV) 15 See to it that no one fails to obtain the grace of God; that no “root of bitterness” springs up and causes trouble, and by it many become defiled;
“Root of bitterness”? What on earth could he be talking about?
(Deu 29:18b-20 ESV) Beware lest there be among you a root bearing poisonous and bitter fruit, 19 one who, when he hears the words of this sworn covenant, blesses himself in his heart, saying, ‘I shall be safe, though I walk in the stubbornness of my heart.’ This will lead to the sweeping away of moist and dry alike. 20 The LORD will not be willing to forgive him, but rather the anger of the LORD and his jealousy will smoke against that man, and the curses written in this book will settle upon him, and the LORD will blot out his name from under heaven.
Rebellion — engaging in known sin in reliance of God’s supposed grace — damns.