For the word of God is living, and powerful, and sharper than any two-edged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart.
For the word of God is living Some understand by the word of God, the eternal word, or Son of God: (to whom may apply all in the 12th and 13th verses) but others rather expound it of the words, promises, and menaces of God, either foretold by the prophets, or preached by the apostles. (Witham)
All this language is metaphorical, but perfectly well understood by the Jews. In their sacrifices, the Levites made use of a two-edged knife to separate from the victim what was for God, what was for the priests, and what was for the people. Thus in sacrificing sinners to the justice of God, Jesus Christ, like a two-edged knife, will separate what is for God, and what is for man; i.e. whatever is good or evil in the whole of man's conduct.
In the next place, lest hearing [the words] after the same [example], you should think that the punishment is the same, hear what he adds; For the Word of God is quick and powerful, and sharper than any two-edged sword, and pierces even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart. In these words he shows that He, the Word of God, wrought the former things also, and lives, and has not been quenched.
Do not then when hearing the Word, think of it lightly. For He is sharper, he says, than a sword. Observe His condescension; and hence consider why the prophets also needed to speak of saber and bow and sword. If you turn not, it is said, He will whet His sword, He has bent His bow and made it ready. Psalm 7:12 For if now, after so long a time, and after their being perfected, He cannot smite down by the name of the Word alone, but needs these expressions in order to show the superiority [arising] from...
