11 For both He who sanctifies and those who are being sanctified are all of one, for which reason He is not ashamed to call them brethren,
Verses 11–16 show that Jesus’ sacrifice was possible only by His becoming human. This identity with humanity is at the core of the argument in verses 11–13. His sufferings brought some wonderful results for those who believe on Him.
The “for” here connects this verse with verse 10 (He 2:10). The author here introduced the grounds for bringing many sons to glory. The incarnation was a prerequisite for Jesus suffering on the cross.
both He [Christ] who sanctifies
The Greek word “sanctifies” means to set apart. Jesus sets apart those who come to Him for salvation (He 9:13-14; 10:10, 14; 13:12). He sanctifies them by His sacrificial death. Jesus sets believers apart by His death to pay for sin. This is positional sanctification, not progressive (He 10:10, 29). Positional salvation means that God declared us completely set apart unto Himself at salvation.
Positional sanctification happened at a point in the past, the point when we trusted Christ for salvation. Positionally, we are set apart like God is set apart; we are right as God is right (justification).
The sanctification here relates to Christ’s priestly offering of Himself on the cross. We are redeemed and cleansed by the interceding blood of the incarnate Christ. That makes us suitable to enter God’s presence; we have been uniquely and eternally set apart from sin.
and those [the redeemed] who are being sanctified
There is a progressive aspect to sanctification as well. This is the total progressive experience of the Christian life from the point of salvation until the person reaches glory. “Being sanctified” is not an event but a life-long process.
are all of [out of] one [neuter, from common humanity],
Jesus and those who believe in Him are “one.” Both the Lord Jesus and believers are out of one source, a common humanity. This brings a unity between them. There is also a dignity that comes by being a member of God’s family.
The word “all” indicates that the Son who sanctifies and those sanctified have one origin (Ac 17:26, Adam). Christ in His humanity and believers share a common descent from Adam. This was not true of angels.
for which reason
This phrase gives the justification for calling believers “brethren.”
He is not ashamed to call them brethren [literally, from the same womb],
The oneness that Jesus brought to His brethren makes them a family of which He is proud. Notwithstanding His eternal dignity as God, Jesus is not ashamed to call believers His “brethren.” Since members of the church share in Christ’s crucifixion, they themselves now have a dignity of which Jesus is not ashamed (He 11:16).
Christ is not ashamed to call the redeemed His brothers because He associated with them in His incarnation. He stepped into their level of humanity and identified with them. He paid for their sin as one of them. Our brotherhood rests both on His incarnation and His crucifixion (Php 2:5f; 2 Co 8:9). He is “the first-born among many brethren” (Ro 8:29). This brotherhood is first with Him and then with each other.
Our solidarity with Christ rests on our redemption through the cross.
Believing in Christ’s death for our sins makes the sons of men the sons of God. There is a majesty in this brotherhood. The Son of God became the Son of Man that He might make the sons of men the sons of God. We are now fellow-heirs with Christ (Ro 8:17).
The Lord became our brother when we believed on Him. He set us apart unto God permanently by giving us positional status with the Father. He put us on the path of sanctification and ultimately to the glory of heaven itself.
Positional sanctification is glory complete, progressive sanctification is glory begun, and ultimate glory is sanctification complete.