Atonement is an important idea in Scripture. "Atonement" is really an Old Testament word, but the principle is only fully developed in the New Testament. This isn't unusual in Scripture: a great deal of the teaching in the New Testament is rooted in the Old Testament. We remember the Lord Jesus' words to Nicodemus: "Thou art the teacher of Israel and knowest not these things" (John 3:10, DBY). Not everything in the New Testament is in the Old, but the New Testament is certainly based in the Old.
What is redemption? It's a word we used to hear a lot in Christian circles, but maybe we don't hear it so much any more. When Scripture talks about redemption, it talks about giving up one thing for another.
Our redemption came at the cost of the blood of Christ Jesus.
What is Justification? It's a word we read mainly in Romans, where we read that God justifies the ungodly (Romans 4:5) . We read that having been justified by faith we have peace with God (Romans 5:1).
There is precisely one Man that is righteous. There is exactly one Man that God can honestly look at and justify. And this is the foundation of the entire doctrine of justification.
What is justification? It is the judge saying "Not Guilty!"
I spent the last week at Shallowbrook Farm in Bradford, IL. I was there for a week of meetings to single young believers with an emphasis on intensive bible study and fellowship. There were several speakers and I wanted to get down on "paper" what was discussed so hopefully it will sink in.