Thomas Aquinas Commentary Hebrews 3:12-19

"Take heed, brethren, lest haply there shall be in any one of you an evil heart of unbelief, in falling away from the living God: but exhort one another day by day, so long as it is called To-day; lest any one of you be hardened by the deceitfulness of sin: for we are become partakers of Christ, if we hold fast the beginning of our confidence firm unto the end: while it is said, To-day if ye shall hear his voice, Harden not your hearts, as in the provocation. For who, when they heard, did provoke? nay, did not all they that came out of Egypt by Moses? And with whom was he displeased forty years? was it not with them that sinned, whose bodies fell in the wilderness? And to whom sware he that they should not enter into his rest, but to them that were disobedient? And we see that they were not able to enter in because of unbelief." — Hebrews 3:12-19 (ASV)

Above, the Apostle showed on the authority of the Psalmist that Christ must be obeyed strictly. In that passage, he found three things: the exhortation, the guilt, and the punishment. He now explains these in that order: first, the exhortation; second, the guilt (see verse 16); and third, the punishment (see verse 18). Regarding the first point, he does two things: first, he exhorts them to be carefully attentive; and second, to engage in mutual exhortation (see verse 12).

Therefore, he says to take care. For everyone should consider the state in which they are: Let everyone prove his own work (Galatians 6:4); See your ways in the valley (Jeremiah 2:23). Therefore, take care, brothers, each one for himself, because each is part of the assembly. As Scripture says, to each one God gave commandment concerning his neighbor . Take care—that is, let one test the other—lest there be in any of you an evil, unbelieving heart leading you to fall away from the living God.

He says this as if to say: many of you are in a mature state, yet because of weakness and free will, evil could be present in some of you. Behold, they that serve him are not steadfast; and in his angels he found wickedness. How much more shall they that dwell in houses of clay, who have an earthly foundation? (Job 4:18–19); Have I not chosen you twelve, and one of you is a devil? (John 6:71). Therefore, no one should be concerned for himself only, but also for each member of his group.

But why do this? So that there will not be an evil, unbelieving heart in any of you. This is the evil the Apostle speaks of: an unbelieving heart, that is, a heart not firm in faith. Wickedness consists in this, for just as the soul’s good consists in clinging to God—It is good for me to adhere to my God (Psalms 72:28)—through faith, so a person’s evil consists in withdrawing from God: Know and see that it is an evil and a bitter thing for you to have left the Lord, your God (Jeremiah 2:19).

He also speaks of “falling away,” because one departs from the living God through unbelief: They have forsaken me, the fountain of living water (Jeremiah 2:13). He says “from the living God” because God is life in Himself and is the life of the soul—In him was life (John 1:4). He says this to show that by withdrawing from God, a person incurs spiritual death.

But if that evil is found in anyone, should they despair? No, they should be admonished all the more. Therefore, he says, but exhort one another every day—that is, continually—by discussing matters of conscience and by encouraging one another to do good, as long as it is called today. This means while the present time of grace lasts: I must work the works of him that sent me, whilst it is day (John 9:4). This is done so that none of you be hardened through the deceitfulness of sin.

For, as stated previously, the heart is hardened by persisting in evil. A person clings to sin because he is deceived. It is natural for the appetite to cling to what is good, but it withdraws from the good because it is deceived: They err who work evil (Proverbs 14:22); I have strayed from the path of truth .

Then, in verse 14, he explains their condition. It is as if he is saying: Our condition is more powerful than theirs, because they only heard, whereas we share in Christ. And he speaks correctly, because in the Old Testament there was only hearing, and grace was not conferred ex opere operato. But in the New Testament, there is both the hearing of faith and the grace given to the one who acts. Therefore, we are partakers of grace in three ways:

1. By accepting the faith: That Christ by faith may dwell in your hearts (Ephesians 3:17).
2. By the sacraments of faith: As many of you as have been baptized in Christ have put on Christ (Galatians 3:27).
3. By partaking of the body of Christ: The bread which we break, is it not the partaking of the body of Christ? (1 Corinthians 10:16).

It should be noted that there are two ways of sharing in Christ: one is imperfect, through faith and the sacraments; the other is perfect, through the presence and vision of the reality itself. The first we already possess in reality; the second we possess in hope. But because hope has the condition that we must persevere, he says, if only we hold our first confidence firm unto the end.

For whoever is baptized into Christ receives a new nature, and Christ is somehow formed in him: My little children, of whom I am in labor again, until Christ be formed in you (Galatians 4:19). This will be truly completed in us in heaven, but here it is only a beginning. This beginning comes through a “formed faith,” because an “unformed faith” is dead: Faith without works is dead (James 2:26). Therefore, unformed faith is not the beginning of partaking in Christ, but formed faith is. As it is written, Faith is the substance of things to be hoped for—that is, the foundation and the beginning.

He says, therefore, that we are partakers of Christ, yet only if we hold our first confidence firm unto the end. But it seems that fear is the beginning, because it says in Psalm 110: The fear of the Lord is the beginning of wisdom. I answer that faith is formed by love, but love does not exist without a reverent fear. Therefore, a formed faith always has love connected to it. Thus, both faith and fear are the beginning.

Then, when he says, who were they that heard, he explains what he had said about their sin. It is as if to say: “You are made partakers of Christ if you do not harden your hearts, as they did who heard and yet were rebellious. Was it all of them? No, not all, for two—Caleb and Joshua—remained and encouraged the others.”

From this, we are given to understand that since the entire Church does not fall, but only some members do, the wicked are punished, but not the good. This is seen in the case of those two: And I will leave me seven thousand men in Israel, whose knees have not been bowed before Baal (1 Kings 19:18); There is a remnant saved according to the election of grace (Romans 11:5).

Then, in verse 17, he explains what he had said about the punishment. He says, therefore: With whom was he provoked forty years? Was it not with them that sinned? From this, it is clear that “forty years” refers to the statement, I was provoked. Therefore, he says that God was offended throughout those forty years. Here it should be noted that all who left Egypt died in the desert, as stated in Joshua 5:4, but not all were “laid low”; only some were. Some were struck down by God, as when the earth opened and swallowed Dathan and Abiram (see Psalm 77); others were struck down by Moses, as with the construction of the golden calf (see Exodus 32); still others were killed by enemies, and some died a natural death. Therefore, not all were struck down. Thus, it was not a universal punishment, although it was general enough that only two entered the promised land.

And concerning that land, he asks, and to whom did he swear—that is, firmly decree—that they should never enter into his rest, but to them that were incredulous? From this, it is clear that they could not enter His rest because of their unbelief. Therefore, he concludes, we see that they could not enter because of their unbelief. We “see” this either from our own experience or by observing their punishment.