But that which beareth thorns and briars is rejected - That is, by the farmer or owner. It is abandoned as worthless. The force of the comparison here is, that God would thus deal with those who professed to be renewed if they should be like such a worthless field.
And is nigh unto cursing - Is given over to execration, or is abandoned as useless. The word "cursing" means devoting to destruction. The sense is not that the owner would curse it "in words," or imprecate a curse on it, as a man does who uses profane language, but the language is taken here from the more common use of the word "curse" - as meaning to devote to destruction. So the land would be regarded by the farmer. It would be valueless, and would be given up to be overrun with fire.
Whose end is to be burned - Referring to the land. The allusion here is to the common practice among the Oriental and Roman agriculturists of burning bad and barren lands. An illustration of this is afforded by Pliny. "There are some who burn the stubble on the field, chiefly upon the authority of Virgil; the principal reason for which is, that they may burn the seeds of weeds;" Nat. Hist. xviii. 30. The authority of Virgil, to which Pliny refers, may be found in Georg. i. 84:
"Saepe etiam steriles incendere profuit agros,
Atque levem stipulam ciepitantibus urere flammis."
"It is often useful to set fire to barren lands, and burn the light stubble in crackling flames." The purpose of burning land in this way was to render it available for useful purposes; or to destroy noxious weeds, and thorns, and underbrush. But the object of the apostle requires him to refer merely to the "fact" of the burning, and to make use of it as an illustration of an act of punishment. So, Paul says, it would be in the dealings of God with his people. If after all attempts to secure holy living, and to keep them in the paths of salvation, they should evince none of the spirit of piety, all that could be done would be to abandon them to destruction as such a field is overrun with fire. It is not supposed that a true Christian will fall away and be lost, but we may remark.
(1) that there are many professed Christians who seem to be in danger of such ruin. They resist all attempts to produce in them the fruits of good living as really as some pieces of ground do to secure a harvest. Corrupt desires, pride, envy, uncharitableness, covetousness, and vanity are as certainly seen in their lives as thorns and briars are on a bad soil. Such briars and thorns you may cut down again and again; you may strike the plow deep and seem to tear away all their roots; you may sow the ground with the choicest grain, but soon the briars and the thorns will again appear, and be as troublesome as ever. No pains will subdue them, or secure a harvest. So with many a professed Christian. He may be taught, admonished, rebuked, and afflicted, but all will not do. There is essential and unsubdued perverseness in his soul, and despite all the attempts to make him a holy man, the same bad passions are continually breaking out anew.
(2) such professing Christians are "nigh unto cursing." They are about to be abandoned forever. Unsanctified and wicked in their hearts, there is nothing else which can be done for them, and they must be lost. What a thought! A professing Christian "nigh unto cursing!" A man, the efforts for, whose salvation are about to cease forever, and who is to he given over as incorrigible and hopeless! For such a man - in the church or out of it - we should have compassion. We have some compassion for an ox which is so stubborn that he will not work - and which is to be put to death; for a horse which is so fractious that he cannot be broken, and which is to be killed; for cattle which are so unruly that they cannot be restrained, and which are only to be fattened for the slaughter; and even for a field which is desolate and barren, and which is given up to be overrun with briars and thorns; but how much more should we pity a man all the efforts for whose salvation fail, and who is soon to be abandoned to everlasting destruction!

That which beareth thorns and briers is rejected - That is: The land which, notwithstanding the most careful cultivation, receiving also in due times the early and latter rain, produces nothing but thorns and briers, or noxious weeds of different kinds, is rejected, αδοκιμος, is given up as unimprovable; its briers, thorns, and brushwood burnt down; and then left to be pastured on by the beasts of the field. This seems to be the custom in husbandry to which the apostle alludes. The nature of the case prevents us from supposing that he alludes to the custom of pushing and burning, in order to farther fertilization. This practice has been common from very early times: -
Saepe Etiam Steriles Incendere Profuit Agros;
Atque Levem Stipulam Crepitantibus Urere Flammis.
Virg. Geor. I., 5:84.
Long Practice Has A Sure Improvement Found,
With Kindled Fires To Burn The Barren Ground;
When The Light Stubble To The Flames Resign'd,
Is Driven Along, And Crackles In The Wind.
Dryden.
But this, I say the circumstances of the case prevent us from supposing to be intended.
Is nigh unto cursing - It is acknowledged, almost on all hands, that this epistle was written before the destruction of Jerusalem by the Romans. This verse is in my opinion a proof of it, and here I suppose the apostle refers to that approaching destruction; and perhaps he has this all along in view, but speaks of it covertly, that he might not give offense.
There is a good sense in which all these things may be applied to the Jews at large, who were favored by our Lord's ministry and miracles. They were enlightened by his preaching; tasted of the benefits of the heavenly gift - the Christian religion established among them; saw many of their children and relatives made partakers of the Holy Ghost; tasted the good word of God, by the fulfillment of the promise made to Abraham; and saw the almighty power of God exerted, in working a great variety of miracles. Yet, after being convinced that never man spake as this man, and that none could do those miracles which he did, except God were with him; after having followed him in thousands, for three years, while he preached to them the Gospel of the kingdom of God; they fell away from all this, crucified him who, even in his sufferings as well as his resurrection, was demonstrated by miracles to be the Son of God; and then to vindicate their unparalleled wickedness, endeavored to make him a public example, by reproaches and blasphemies. Therefore their state, which had received much moral cultivation from Moses, the prophets, Christ, and his apostles; and now bore nothing but the most vicious fruits, pride, unbelief, hardness of heart, contempt of God's word and ordinances, blasphemy, and rebellion; was rejected - reprobated, of God; was nigh unto cursing - about to be cast off from the Divine protection; and their city and temple were shortly to be burnt up by the Roman armies. Thus the apostle, under the case of individuals, points out the destruction that was to come upon this people in general, and which actually took place about seven years after the writing of this epistle! And this appears to be the very subject which the apostle has in view in the parallel solemn passages, Hebrews 10:26-31; and, viewed in this light, much of their obscurity and difficulty vanishes away.

But that which beareth thorns and briers,.... To which wicked men answer; who are unfruitful and unprofitable, and are hurtful, pricking and grieving, by their wicked lives and conversations, by their bitter and reproachful words, and by their violent and cruel persecutions; and particularly carnal professors, and especially apostates, such as before described; for to such earth, professors of religion may be compared, who are worldly, slothful, defrauding and overreaching, carnal and wanton; as also heretical men, and such as turn from the faith, deny it, and persecute the saints: and the things or actions produced by them are aptly expressed by "thorns and briers"; such as errors, heresies, and evil works of all kinds; and which show that the seed of the word was never sown in their hearts, and that that which they bear, or throw out, is natural to them: and such earth is
rejected; as such men are, both by the church, and by God himself; or "reprobate", as they are concerning the faith, and to every good work; and are given up by God to a reprobate mind: and is "nigh unto cursing"; and such men are cursed already by the law, being under its sentence of curse and condemnation; and are nigh to the execution of it; referring either to the destruction of Jerusalem, which was near at hand; or to the final judgment, when they shall hear, Go, ye cursed:
whose end is to be burned; with everlasting and unquenchable fire, in the lake which burns with fire and brimstone.

that which--rather as Greek (no article), "But if it (the 'land,' Hebrews 6:7) bear"; not so favorable a word as "bringeth forth," Hebrews 6:7, said of the good soil.
briers--Greek, "thistles."
rejected--after having been tested; so the Greek implies. Reprobate . . . rejected by the Lord.
nigh unto cursing--on the verge of being given up to its own barrenness by the just curse of God. This "nigh" softens the severity of the previous "It is impossible," &c. (Hebrews 6:4, Hebrews 6:6). The ground is not yet actually cursed.
whose--"of which (land) the end is unto burning," namely, with the consuming fire of the last judgment; as the land of Sodom was given to "brimstone, salt, and burning" (Deuteronomy 29:23); so as to the ungodly (Matthew 3:10, Matthew 3:12; Matthew 7:19; Matthew 13:30; John 15:6; 2-Peter 3:10). Jerusalem, which had so resisted the grace of Christ, was then nigh unto cursing, and in a few years was burned. Compare Matthew 22:7, "burned up their city" an earnest of a like fate to all wilful abusers of God's grace (Hebrews 10:26-27).

That which beareth thorns and briers - Only or chiefly. Is rejected - No more labour is bestowed upon it. Whose end is to be burned - As Jerusalem was shortly after.