The Spirit himself bears witness with our Spirit that we are children of God.
Romans 8:16 NASB
When we come to Christ, God not only forgives us, he also adopts us. Through a dramatic series of events, we go from condemned orphans with no hope to adopted children with no fear. Here is how it happens. You come before the judgement seat of God full of rebellion and mistakes. Because of his justice he cannot dismiss your sin, but because if his love he cannot dismiss you. So, in an act which stunned the heavens, he punished himself on the cross for your sins. God's justice and love are equally honored. And you, God's creation, are forgiven. But the story doesn't end with God's forgiveness...
It would be enough if God just cleansed your name, but he does more. He gives you HIS name.