Question about Christ's death on the cross

[Antisera]

So I haven't asked this to anyone in my community because I feel like it's kind of an embarrassing thing that I don't know the answer to this, since it seems like everyone else does. How was Christ's death a sacrifice? I understand that God the Father pardoned the elect from their sins on behalf of Christ, but I don't understand why it's seen as a sacrifice since He was exalted after His death (which he surely would have known would happen). He wet back to Earth to see the apostles and back to heaven as though he had never "died", so nothing really changed. Was His sacrifice the pain of His death and the pain of bearing our sin? Or the three days separated from God the Father before his ressurection?

Hopefully you can tell that I'm not trolling or trying to start some kind of argument with my question.