The term atonement in Christian theology refers to the Triune God‘s acting in human history to reconcile the original relationship between God and man that was broken due to sin. Biblically, to atone means to make amends and reconcile whereby the guilt of man is removed. In the Old Testament, atonements were offered by the high priest but were only temporary and had to be offered repeatedly. They foreshadowed the real and final atonement made by Jesus Christ on the cross where He atoned for the sins of the world (1 John 2:2) and, when one receives and accepts this atonement by faith (Ephesians 2:8-9), they are reconciled to God (Romans 5:9-11) and have peace with Him (Romans 5:1).
Man is a sinner (Romans 3:23; 5:8) and cannot atone for himself. Therefore, God the Father, in His love for humanity sent His Son (1 John 4:10) to die in our place (1 Pet. 3:18) for our sins (1 Pet. 2:24). It is because of the atonement that our fellowship with God is restored.
The atonement was completed on the cross, where the blood of Christ was shed (Hebrews 9:22) and where sin was “put away” entirely (Hebrews 9:26). This is why part of the promise of the New Covenant is that God remembers believers sins no more (Jeremiah 31:31-4). This is much different than the Adventist teaching.
The SDA Church does not mean this when they use the term “atonement.” As can be seen in Salvation: Contours of Adventist Soteriology, a scholastic work by SDA scholarship, Jon Paulien explains what the they mean:
One of the most debated topics of Christian theology is expressed in these questions: Why the cross? What really happened at the cross? The answers to these questions have been widely debated under the general heading of the atonement. But when Seventh-Day Adventists (SDA) approach the matter of atonement, an immediate dilemma is perceived. When Adventists talk about atonement, they refer specifically to what Jesus is doing now in the heavenly sanctuary. On the other hand, when scholars outside the Seventh-Day Adventist Church discuss the atonement, they refer specifically to the cross of Jesus Christ and what God was doing there.
Jon Paulien, Salvation: Contours of Adventist Soteriology, Chapter 10, pg. 189
Atonement in Adventist theology is referring to the investigative judgment. This is to say the SDA Church teaches that the cross of Christ was only where the atoning sacrifice took place, not where man was reconciled to God and propitiation accomplished. Their primary appeal in this area is to the Levitical Priesthood work—namely the alleged transference of sin, in type, by the priests into the sanctuary.
You can read more about this here.
