The word atonement in the Hebrew is literally "to cover," and refers to the removal of positive guilt out of God's sight.
Atonement then refers to the cross where expiation (full payment) was made for sin.
The holiness of God's nature demanded the judgment of sin. The love of God provided a sacrifice.
All the claims of God as "light" have been met at the cross, so that God is free to come out in the fullness of His grace; therefore the riches of His grace are now made known in the present blessing of every one that has believed the gospel.
The knowledge of it is through faith in the Word of God. The enjoyment of it is the result of walking in the path of obedience to the Word, so that the Holy Spirit can without hindrance fill our hearts with the precious love of Christ, and our minds with the fruit of His atoning work, that has glorified God in the putting away of our sins.
THE ATONING work is done,
The Victim's blood is shed;
And Jesus now is gone
His people's cause to plead:
He sits in heaven their great High Priest,
And bears their names upon His breast.
See "sprinkled with the blood
The mercy seat" above;
For justice had withstood
The purposes of love;
But justice now withstands no more,
And mercy yields her boundless store.
And though awhile He be
Hid from the eyes of men,
His people look to see
Their great High Priest again.
In brightest glory He will come,
And take His waiting people home.