Does our union with Christ have anything to say about Christian social justice? Todd Billings in chapter 4 of Union with Christ makes this vital connection:
"According to Calvin, the 'sum of the gospel' is the double grace of justification and sanctification, gifts that are inseparable yet distinct, received by the Spirit in union with Christ. With this view of the gospel . . . love of neighbor and, consequently, justice are folded in as an essential feature of the Spirit’s work of regeneration. A life of justice is not an optional part of the Christian life . . ." (107)
In Christ, believers are justified and sanctified, acquitted and made new. As Paul says: “Or don’t you know that all of us who were baptized into Christ Jesus were baptized into his death? We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life” (Rom 6:3-4). This “new life” is geared toward righteousness—personal and public righteousness. Part of what it means to be sanctified or regenerated in Christ is to have a new orientation, a new direction in life, namely, to seek your neighbor’s good, which may involve acts of “social justice.” If we have been united to Christ, then we will pursue justice, or at least should pursue it, instead of succumbing to the temptation to ignore injustice.