If a person is reconciled to God, its because their "Faith has been counted by God as (Christ's) righteousness.
Therein lies the reconciliation.
This means that God has accepted the Believers faith in Jesus, and then provides this..
A.) = "GOD who started salvation ....in the born again.... shall Himself be faithful to complete it".
So, that is all related to the finished work of Jesus on the Cross.
A person comes to Christ, and they choose to believe in Jesus, and God sees that faith in their Heart and accepts it, to then apply the NEW COVENANT .. .the Blood atonement.. .to them, as "Imputed righteousness"..
2 Corinthians 5, tells the born again that we are the "ministers of reconciliation"... we are to tell unbelievers that God, through Christ has made it possible for them to be reconciled to God... "BY FAITH in Christ".