Was the Day of Atonement in Leviticus actually a day of atonement for Israel?

No. Although translators labeled Leviticus 16 the Day of Atonement, it was not actually a day of atonement for Israel; no true atonement existed until Christ died. It should have been called the Day of Covering, since it pictured what Christ would fulfill.

Les explains that the Day of Atonement in Leviticus 16 beautifully pictures what John’s Gospel and Hebrews show: Christ fulfilled every detail. The translators’ name is unfortunate because it was not a Day of Atonement for Israel; there was no atonement until Christ died. It should have been called the Day of Covering. Everything pictured in the tabernacle in type was fulfilled to the last jot and tittle by Christ, who became our high priest and presented His blood. Now believers have an advocate with the Father, Jesus Christ the righteous; when we sin, we confess it, and He points to the blood.

Leviticus 16

Why does the Day of Atonement matter for understanding Christ's work?

The Day of Atonement matters because it pictures Christ's high-priestly work in every detail. Its tabernacle types were fulfilled by Christ, who presented His blood as propitiation and advocate. Though called Atonement, it was really a Day of Covering, since true atonement came only when Christ died.