I have not reached a satisfactory understanding of the Atonement, but I think I perceive some of the necessary ingredients.
1. Jesus was Jehovah
Christ is the Jehovah of the Old Testament - which means he created the earth and everything in it - he set-up the situation which Men inhabit.
This was in accordance with his Father's plan - a plan which culminated in Christ's incarnation and entering the world he himself made, as the Man Jesus of Nazareth (presumably, temporarily handing-over the Lordship of this world to his Father); and led to the Atonement where he became our saviour - after which Christ resumed his Lordship of this world.
2. We were saved by Christ in the sense of saved from an eternity as disembodied witless spirits (in Sheol) and enabled to have eternal life, in resurrected bodies, living in Heaven with Jesus himself as His siblings (potentially also with our 'families', however that term is defined).
3. But how did the Atonement 'work'?
Christ was the scapegoat, who took our sins upon himself. He did this voluntarily, from love - and it seems to have happened (in Time) in the Garden of Gethsemane and on The Cross.
In a once for all act, Christ accepted all the sins of the world ever.
But that was not the end of the matter. We were saved potentially, but only potentially - something more was needed from each person for the process to be completed - each person must make the choice to accept salvation.
What does this salvation entail?
We, each of us, must put-our-sins-onto Christ - analogously as sins were put-onto the scapegoat (before he was driven into the wilderness) or onto the sacrificial lamb.
This is repentance; because to put our sins onto Christ we must first acknowledge that they were indeed sins; and by the putting-upon we acknowledge and trust the Lordship and necessity of Christ - and that our salvation is only by Him.
It is His love for us which made him want this and made this process possible, and it is our love for Him which makes the process Good, when it is done with gratitude, sorrow and compassion - then joy.