One of the great Biblical atonement metaphors is that of reconciliation. In 2 Cor 5:18, 19 we find that Christ reconciled the world to Himself by “not counting our sins against us”. Rom 5:10, 11 teaches that sinners were reconciled to God by Christ’s death. Further, a comparison with v9 shows that justification and reconciliation are used in parallel.
This is all summed up in the what is known as the great divine exchange of 2 Cor 5:21 -
God made Him who knew no sin to be sin on our behalf, so that in Him
we might become the righteousness of God.
That is, Christ so identified with us that he took responsibility of our sin!
This metaphor of family reconciliation is based on two parallel ideas of Hebrew idiom:
- Jesus is our brother (Heb 2:11-13, Ps 22:22, Isa 8:17, 18, Matt 12:48, 49, John 20:17, Rom 8:29)
- sin separates us from Jesus our brother (Isa 59:2, Gal 5:4, Eph 2:12, Ps 22:1, Eze 14:5, Jer 6:8).
Thus, as our beloved brother, Jesus takes responsibility for the family reconciliation, and reconciles us to God by His sacrificial death.
This is further reinforced by forgiven sinners being called "children of God", 1 John 3:1-3, 10, 5:2, John 11:52, Rom 8:16, 14, 9:8, Gal 3:26, Matt 5:9, Phil 2:15, Heb 2:13, etc. As children of God we can call the Son of God our brother.
Supplementary note: The fact that Jesus is called the "Son of God" does not make Him any less God because He is called "the God" (ho theos) in places like Matt 1:23, John 20:28, and equal to the Father in other places such as John 1:18, 5:17, 18, 23, 10:30, Phil 2:5-8, 1 Tim 3:16, Titus 2;13, Heb 1:8, 9, 2 Peter 1:1, Isa 9:6, 7, etc.