Atonement (כפר - koper)
The primary meaning of "atonement" is "to cover." Under the Mosaic Law, those who sinned were required to offer a sacrifice that would atone (cover) for their sin. Additionally, the High Priest made a yearly atonement for any sins committed unknowingly by the nation of Israel, as ignorance of the law was not an excuse for violating it (Exodus 30:10; Leviticus 4:1-3). This concept of "covering" is also expressed in a psalm of David, where he writes of God, who listens to prayer and covers transgressions. David emphasizes that transgressions of the law had to be dealt with, lest death come upon the one breaking it: "Words of perversity are against me. Our transgressions You cover " (Psalm 65:3).
Within the tabernacle, in the innermost chamber, God designated the place of atonement where the High Priest would enter once a year to offer a sacrifice for the sins of Israel. It is often mistranslated as the mercy seat; however, no mercy was being expressed here. Rather, it served as the covering place (הַכַּפֹּֽרֶת – kap-po-ret) for sins (Leviticus 16:15) and thus was the place of propitiation.
In the New Testament, “atonement” is conveyed by the term “propitiation”, as seen in Hebrews 9:5 regarding the place of atonement in the Temple. One of the aspects of Christ’s work on the cross was providing a propitiation concerning the deferral of previous sins committed. “Whom God before set forth a propitiation through the faith by His blood unto a demonstration of His righteousness because of the deferral of punishment of the sins having previously happened ”(Romans 3:25). However, regarding sins, Christ did not merely cover them—He sent them away (forgave them). There is a significant difference between what the blood of Christ accomplished and what the blood of bulls and goats could achieve, as the latter could not inherently remove sin (Hebrews 10:4). Under the New Covenant, made through the blood of Christ, our sins are sent away, not merely covered." James uses a form of the word “covering” when referring to someone who turns a sinner from his error, covering (καλύπτω) a multitude of sins (James 5:20). Therefore, if Christ had merely made an atonement for sins, this would have been explicitly conveyed in the New Testament.
Under the Old Testament, God deferred dealing with sin until the appropriate time; therefore, a covering was needed for transgressions. Under grace, there is no transgression, for where there is no law, there is no transgression (Romans 4:15).
Through Christ’s death on behalf of our sins, He did not merely cover our sins; He completely removed them. In Whom we have the full redemption, the sending away of sins – Colossians 1:14. Even now when we sin, once we verbally agree with God concerning our action as being sinful, He is faithful and just to send away that sin and to cleanse us of all unrighteousness (1 John 1:9). We are under a covenant of grace, and when we walk according to grace, we do not sin (1 John 5:18). However, when we fail and do not live out from faith, God still deals with us in a gracious manner for when we confess the sin, He is faithful to forgive it and cleans us from the unrighteousness that allowed the sin to be birthed. Therefore, we are now saints, not sinners saved by grace, for we are washed of our sins. Since our sins have been sent away, let us walk accordingly, living out the righteousness we now have in Christ.