Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new. Now all things are of God, who has reconciled us to Himself through Jesus Christ, and has given us the ministry of reconciliation, that is, that God was in Christ reconciling the world to Himself, not imputing their trespasses to them, and has committed to us the word of reconciliation.

Now then, we are ambassadors for Christ, as though God were pleading through us: we implore you on Christ's behalf, be reconciled to God. For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him.  

See also Ephesians 2:13-22