I recently read Donald MacLeod's book Compel Them to Come In: Calvinism and the Free Offer of the Gospel. It's a very helpful book on that topic, and I think some of the points he raises in this book can help us as we think about the warning passages in Scripture. In both cases, opponents of Reformed theology claim that certain Reformed theological commitments undermine our ability to deal honestly with certain portions of Scripture. MacLeod's book deals with the alleged contradiction between the Reformed doctrine of total depravity and the free offer of the Gospel.
Reformed churches believe that the Bible teaches a doctrine we refer to as “total depravity.” In the Canons of Dordt, for example, we find this point made:
“Therefore, all people are conceived in sin and are born children of wrath, unfit for any saving good, inclined to evil, dead in their sins, and slaves to sin; without the grace of the regenerating Holy Spirit they are neither willing nor able to return to God, to reform their distorted nature, or even to dispose themselves to such reform” (Third and Fourth Main Point of Doctrine, Article 3).
In other words, fallen human beings are dead in sin and have no ability in and of themselves to believe the Gospel. They are unable to believe apart from God’s sovereign work of regeneration.
And yet, at the same time, these same Canons of Dordt say the following:
“it is the promise of the gospel that whoever believes in Christ crucified shall not perish but have eternal life. This promise, together with the command to repent and believe, ought to be announced and declared without differentiation or discrimination to all nations and people, to whom God in his good pleasure sends the gospel.” (Second Main Point of Doctrine, Art. 5).
and
“all who are called through the gospel are called seriously. For seriously and most genuinely God makes known in his Word what is pleasing to him: that those who are called should come to him. Seriously he also promises rest for their souls and eternal life to all who come to him and believe” (Third and Fourth Main Point of Doctrine, Article 8).
So, we are to indiscriminately proclaim the Gospel of Christ to all without distinction. It is a genuine offer of the Gospel. We know that none hearing the Gospel have the ability in themselves to believe unless God regenerates them, but that doesn’t impact the reality of the genuineness of the Gospel offer. It really is true that whosoever believes in the Lord Jesus Christ will be saved. We aren’t trying to determine who is elect and who isn’t when we proclaim the Gospel because that is impossible. God uses the external call to accomplish the effectual call of His people. Our task is not to try to figure out which are which ahead of time.
How might these principles help us as we consider the so-called "warning passages" of Scripture (e.g. Hebrews 6:4–8, 10:26–31)?
A lot of people think that if the warning passages are genuine warnings, then we have to deny the Reformed doctrine of perseverance of the saints. But just as the genuine offer of the gospel does not require denying total depravity, genuine warnings do not require denying perseverance. When we proclaim the genuine offer of the Gospel or proclaim the genuine warnings of Scripture, we’re not doing so on the basis of any assumed ability to read the hearts of other people and determine who is and isn’t elect. The proclamation of the Gospel is the means by which God calls His elect, and warnings and threats are one of the means by which He preserves His elect (See Canons of Dordt, Fifth Main Point of Doctrine, Art. 14), but neither assumes anything about whether any particular person hearing the promise or the warning is elect.
When we indiscriminately proclaim the Gospel promise, we know that only those whom God regenerates can and will believe, but we don’t know who they are, so the Gospel promise is made indiscriminately. When we indiscriminately proclaim the biblical warnings, we know that the elect do not have the ability to finally and fully fall away, but we don’t know who any of them are, so the warnings are also proclaimed indiscriminately.
Paul can tell sinners in all sincerity: "Whosoever trusts in Christ will be saved." He can also tell professing Christians in the corporate church (which he knows is a mixed body of wheat and tares) in all sincerity: "Whosoever apostatizes will not be saved." Both are genuine and true statements. But these proclamations don’t in themselves address questions of ability or inability. The doctrines of total depravity, regeneration, perseverance, etc. deal with those questions after the fact. They address questions such as: Why did this person believe the Gospel promise and this one did not? Why did this person apostatize and this one did not?
As the Canons of Dordt make very clear, the genuine indiscriminate offer of the Gospel does not require rejecting total depravity. And the genuine indiscriminate warning passages do not require rejecting perseverance of the saints.