And we see that they could not enter in, because of unbelief.

“"For some when they had heard did provoke, howbeit not all that came out of Egypt by Moses: And with whom was He grieved forty years? Was it not with them that had sinned, whose carcasses fell in the wilderness? And to whom sware He that they should not enter into His rest, but to them that believed not? So we see, that they could not enter in because of unbelief." After again repeating the testimony, he adds also the question, which makes the argument clear. For he said (he repeats), "To-day if ye hear His voice, harden not your hearts, as in the provocation." Of whom does he speak (he says) as having been hardened? Of whom as not believing? Is it not of the Jews? Now what he says is to this effect. They also heard, as we hear: but no profit came to them. Do not suppose then that by "hearing" what is proclaimed ye will be profited; seeing that they also heard, but derived no benefit because they did not believe. Caleb then and Joshua, because they agreed not with those who did not believe, escaped the vengeance that was sent forth against them. And see how admirably he said, not, They did not agree, but, "they were not mixed" - that is, they stood apart, but not factiously when all the others had one and the same mind. Here it seems to me that a faction too is hinted at.”

“Above, the Apostle showed, by the authority of the Psalmist, that Christ must be firmly obeyed. But in that authority he set down three things: admonition, fault, and punishment; here he expounds these three in order. He does the first here, "see"; the second there, "but some"; the third there, "but to whom did he swear." In the admonition, however, there are two things, namely, the admonition itself, and the condition of that admonition. Hence he expounds these two. First the first, here; second the second, there, "for partakers of Christ." But in the first admonition he exhorts to two things: namely, to careful consideration; second, to mutual admonition, there, "but exhort." He says therefore, "see." For each one ought to consider in himself in what state he is. Gal. 6:4: "let each one prove his own work." Jer. 2:23: "see your ways in the valley." "See," therefore, brethren, as regards each one in himself, because each one is a part of the society, and God has commanded each one concerning his neighbor, Ecclus. 17:12. "See," that is, test one another, "lest perhaps there be in any of you," etc., as if to say: many among you are in a state of perfection, yet on account of frailty and the freedom of the will there could be evil in some of you. Job 4:18f.: "behold, they that serve him are not steadfast, and in his angels he found perverseness: how much more they that dwell in houses of clay, and have an earthly foundation?" Jn. 6:71: "did I not choose you twelve, and one of you is a devil?" Therefore let no one be solicitous only for himself, but also for each one of his society. But what? "Lest there be in any of you an evil heart of unbelief." Behold the evil of which the Apostle speaks, namely, an unbelieving heart, that is, not firm in faith, in which the malice of the soul consists: for as the good of the soul is in cleaving to God — Ps. 72:27: "but it is good for me to adhere to God," which, namely, is through faith — so to withdraw from God through unbelief is the evil of man. Jer. 2:19: "know and see, O Israel, that it is an evil and bitter thing that thou hast left the Lord," etc. And therefore he says "of departing," because through unbelief one withdraws from the living God. Jer. 2:13: "they have forsaken me, the fountain of living water." But he says "from the living God," because he is both life in himself and the life of the soul. Jn. 1:4: "in him was life." He says this in order to show that through withdrawal from God, man incurs spiritual death. But if this evil is found in someone, is one therefore to despair? No, but rather he ought to be exhorted, that is, admonished: therefore he says, "but exhort one another every day," that is, continually, namely by examining one's own conscience, and leading it to the good, "while it is called today," that is, as long as the present time of grace lasts, which is all as it were one day. Jn. 9:4: "I must work the works of him that sent me, while it is day." And this is so that none of you may be hardened by the deceitfulness of sin. For as was said above, the heart is hardened through obstinacy in evil. But by this someone clings firmly to sin, because he is deceived. For it is natural to the appetite to cling to the good; but it withdraws from the good because it is deceived. Prov. 14:22: "they err that work evil"; and Prov. 13:13, according to another text: "deceitful souls err in sins." Wis. 5:6: "therefore we have erred from the way of truth." Consequently, when he says "partakers," etc., he expounds the condition of the admonition, as if to say: this condition is more effective than that one, because they only heard, but we have been made partakers of Christ. And he speaks properly, because in the Old Testament there was only hearing, nor was grace conferred from the work performed; but in the New Testament there is both the hearing of faith and grace is given to the one performing it. Hence we have been made partakers of Christ. Jn. 1:16: "of his fullness we have all received." But we are partakers of grace, first through the reception of faith. Eph. 3:17: "that Christ may dwell through faith in your hearts." Second, through the sacraments of faith. Gal. 3:27: "as many of you as have been baptized in Christ, have put on Christ." Third, through participation in the body of Christ. 1 Cor. 10:16: "the bread which we break, is it not the participation of the body of the Lord?" But it must be known that participation in Christ is twofold. One imperfect, which is through faith and the sacraments; the other perfect, which is through the presence and vision of the reality; the first we already have in fact, but the second in hope. Yet along with this, hope has this condition, namely, if we persevere. Hence he says, "if however the beginning," etc. For whoever is baptized in Christ receives a certain new nature, and Christ is in a certain way formed in him. Gal. 4:19: "my little children, whom I bring forth again, until Christ be formed in you." This indeed will be truly perfected in us in our homeland, but here only the beginning, and this through formed faith, because unformed faith is dead. James 2:20: "faith without works is dead." Hence this is not for us the beginning of participation in Christ, but formed faith is. Below, 11:1: "but faith is the substance of things to be hoped for," that is, the foundation, and as it were the beginning. He says therefore: we are partakers of Christ, if however we hold firm unto the end the beginning of his substance, namely formed faith. But on the contrary: it seems that fear is rather the beginning, because it says, Ps. 110:9: "the fear of the Lord is the beginning of wisdom." I respond. It must be said that faith is formed through charity. But charity is not without chaste fear. And therefore formed faith always has this fear attached to it. Hence both faith and fear are the beginning. But that which is added when it is said, "today," etc., has been entirely expounded. Then, when he says "for some who, having heard," he expounds what he had said concerning their fault, as if to say: you have been made partakers of Christ, if you do not harden your hearts as those who heard, but provoked — "but not all," that is, yet not all. For two, namely Caleb and Joshua, remained steadfast, as is found in Num. 14:6, and they also strengthened the others. And through this it is given to understand that, when not the whole Church falls, but only some, even if many, nevertheless the evil will be punished, but not the good, as in those two. 3 Kings 19:18: "I have left me seven thousand men, who have not bowed their knees to Baal." Rom. 11:5: "a remnant have been saved according to the election of God." Then, when he says "but to whom," etc., he expounds what he had said concerning the punishment. And first, that which he had said, "I was offended"; second, that which he had said, "I swore in my wrath," etc., there, "but to whom did he swear," etc. He says therefore, "but with whom was he offended forty years? Was it not," etc. From which it is clear that that which he said above, "forty years," refers to that, "I was offended." Hence he says that he was offended with them for those forty years. Hence it must be known that all who went out of Egypt died in the desert, as is said in Jos. 5:4. Yet not all were struck down; but some indeed by God, as when the earth was opened, and swallowed up Dathan and Abiron, as is said in Ps. 105:17, and concerning this it is found in Num. 16:31ff. Others indeed were struck down by Moses, as is evident in the casting of the calf, as is evident in Ex. 32:16. Others indeed by enemies, as is evident in many places. And these things are sufficiently found in 1 Cor. 10:1ff. Others indeed died their own death. Therefore not all were struck down. Hence it was not a general punishment, but it was a special punishment. And none except those two who have been mentioned entered the land of promise. And concerning this land he says, "but to whom did he swear," that is, firmly decreed, that they should not enter into his rest, except to those who were unbelieving, namely at the words of the spies? Hence it is clear that on account of unbelief they were not able to enter into his rest; and for this reason he says, "we see," because they experienced that on account of their unbelief they were not able to enter. Or, "we see," that is, ourselves, namely through that punishment which has been mentioned, that they were not able, etc.”

“So we see that they could not enter in - It was no decree of God that prevented them, it was no want of necessary strength to enable them, it was through no deficiency of Divine counsel to instruct them; all these they had in abundance: but they chose to sin, and would not believe. Unbelief produced disobedience, and disobedience produced hardness of heart and blindness of mind; and all these drew down the judgments of God, and wrath came upon them to the uttermost. 1. This whole chapter, as the epistle in general, reads a most awful lesson against backsliders, triflers, and loiterers in the way of salvation. Every believer in Christ is in danger of apostasy, while any remains of the evil heart of unbelief are found in him. God has promised to purify the heart; and the blood of Christ cleanses from all sin. It is therefore the highest wisdom of genuine Christians to look to God for the complete purification of their souls; this they cannot have too soon, and for this they cannot be too much in earnest. 2. No man should defer his salvation to any future time. If God speaks to-day, it is to-day that he should be heard and obeyed. To defer reconciliation to God to any future period, is the most reprehensible and destructive presumption. It supposes that God will indulge us in our sensual propensities, and cause his mercy to tarry for us till we have consummated our iniquitous purposes. It shows that we prefer, at least for the present, the devil to Christ, sin to holiness, and earth to heaven. And can we suppose that God will be thus mocked? Can we suppose that it can at all consistent with his mercy to extend forgiveness to such abominable provocation? What a man sows that shall he reap. If he sows to the flesh, he shall of the flesh reap corruption. Reader, it is a dreadful thing to fall into the hands of the living God. 3. Unbelief has generally been considered the most damning of all sins. I wish those who make this assertion would condescend to explain themselves. What is this unbelief that damns and ruins mankind? Their not permitting their minds to be persuaded of the truths which God speaks. Απιστια, from α, negative, and πιστις, faith, signifies faithless or to be without faith. And this is an effect from another cause. In Heb 4:11, these very people are said to have fallen through unbelief; but there the word is απειθεια, from α, negative, and πειθω, to persuade. They heard the Divine instructions, they saw God's stupendous miracles; but they would not suffer themselves to be persuaded, that he who said and did such things would perform those other things which he had either threatened or promised: hence they had no faith, because they were unpersuaded; and their unbelief was the effect of their unpersuaded or unpersuadable mind. And their minds were not persuaded of God's truth, because they had ears open only to the dictates of the flesh; see on Heb 4:2 (note). Here then is the damning sin, the not inferring, from what God has said and done, that he will do those other things which he has either threatened or promised. And how few are there who are not committing this sin daily! Reader, dost thou in this state dream of heaven? Awake out of sleep! 4. Where there are so many snares and dangers it is impossible to be too watchful and circumspect. Satan, as a roaring lion, as a subtle serpent, or in the guise of an angel of light, is momentarily going about seeking whom he may deceive, blind, and devour; and, when it is considered that the human heart, till entirely renewed, is on his side, it is a miracle of mercy that any soul escapes perdition: no man is safe any longer than he maintains the spirit of watchfulness and prayer; and to maintain such a spirit, he has need of all the means of grace. He who neglects any of them which the mercy of God has placed in his power, tempts the devil to tempt him. As a preventive of backsliding and apostasy, the apostle recommends mutual exhortation. No Christian should live for himself alone; he should consider his fellow Christian as a member of the same body, and feel for him accordingly, and have, succor, and protect him. When this is carefully attended to in religious society, Satan finds it very difficult to make an inroad on the Church; but when coldness, distance, and a want of brotherly love take place, Satan can attack each singly, and, by successive victories over individuals, soon make an easy conquest of the whole.”