Christ’s atonement is limited to Christ’s vicarious humanity for the world. As the ‘firstborn from the dead’ He is the second and greater Adam, wherein all of humanity, from 
Christ’s elect humanity, comes to have the capacity, in echo of Christ’s Yes and Amen for us, to say Yes and Amen by the Spirit, to the Father. Christ is God’s unconditionally elect human for the world, and it is in His humanity that we come to have the capacity to truly be human; insofar that the entailments of what it means to be genuinely human is to be in right and reconciled relationship with the triune God. ‘In Him are hidden all the treasures of wisdom and knowledge.’ It is for those who are spiritually in union with Christ (not just carnally or objectively) that God’s election for the world in Christ becomes fully realized and actualized; and this, because it has first been fully realized and actualized in the vicarious humanity, the vicarious repentance, the vicarious faith of Christ pro nobis (for us). See the Koine Greek pistis Christou and the subjective genitive for further exegetical support.