In Hebrews 4.12, we read “For the word of God is living and active, sharper than any two-edged μάχαιραν, piercing to the division of soul and spirit, of joints and marrow, and discerning the thoughts and intentions of the heart.”
This verse is very often quoted and always the “word of God” is thought of as meaning “Scripture.” Yet in the context of Hebrews, the author is not talking about Scripture at all.
Μάχαιραν in this verse is normally translated as “sword.” However, we need to go back and look at the context that this verse is in; entering into God’s rest and the quote from Heb. 4.8:
“For if Joshua had given them rest, God would not speak later of another day.”
In Joshua 5.2 God says to Joshua, "Make flint knives and circumcise the people of Israel again the second time." The word in the Septuagint that is used for “flint knives” is μάχαιραν.
The people need to be circumcised before entering the Promised Land and receiving God’s rest. Yet, this isn’t the definitive rest of God. This rest only comes with Christ and the circumcision of the heart. We see this in Ezekiel 44.6-7 “Thus says the Lord GOD: O house of Israel, let there be an end to all your abominations, in admitting foreigners, uncircumcised in heart” and Collosians 2.11 “In him also you were circumcised with a circumcision made without hands, by putting off the body of flesh in the circumcision of Christ.”
Thus μάχαιραν in this context is better translated as “knife.” And the “word of God” is the λόγος, Christ, who is a living two-edged knife that circumcises the heart allowing us to enter into the Heavenly rest of God, which is the definitive rest.
Then we have verse 13: “And no creature is invisible before him, but all things are naked and exposed to his eyes, with whom on our behalf is the word.”
The “him” in verse 13 refers to God. “Exposed” in Greek has two meanings. The first is a technical term for establishing a wrestling hold on a person. The second is in reference to a sacrificial victim. The neck of the sacrificial victim is exposed in order to be slit with a knife.
“Naked” here refers to the naked neck exposed to God’s eyes.
“With whom on our behalf is the word”: πρὸς pro\s ὃν o(\n ἡμῖν h(mi=n ὁ o( λόγος . The Logos is with God on our behalf. Christ was a victim in a sacrifice and the result of this sacrifice is that He is now with God interceding on our behalf. His expiatory sacrifice satisfied for our sins in the past. But we keep sinning, so Christ intercedes in Heaven for us. Paul continues his argument in verse 14 by saying, “having therefore a great high priest.” Christ has gone through the Heavens and is now interceding for us as the Great High Priest!
In conclusion, Hebrews 4.12-13 shows us the two sides of Christ. We see Him in verse 12 as the Logos performing the efficacious work of the Son in the Sacrament of Baptism in which we receive a circumcision of the heart and enter into God’s rest. Verse 13 shows the efficacious work of the Logos interceding for us as High Priest. Hebrews 4.12 and 4.13 describes the two different functions of the same Logos; the Logos that is like a two-edged knife!