Adoption
In our court system today when a judge pronounces a person "not guilty", the judge's relationship with the accused does not change. The judge may not even like the person. He may have even thought that the defendant was guilty but not enough evidence was presented to support that fact, therefore the "not guilty" verdict.
When God's saves a person by grace alone and declares them justified by faith alone, the Judge (God) declares one "not guilty" he steps down from behind the judge's bench and tells that person, "I am no longer your judge but now your Father and you are no longer the accused but my heir. Come into My living room, come sit at My table, and come enjoy the benefits of being My child".
No matter how many times we err, God will not un-adopt us! Our salvation is secure.