Definition of expiate from Merriam-Webster
1a: to make amends for; permission to expiate their offences by their assiduous labours— Francis Bacon
b: to extinguish the guilt incurred by
2 obsolete : to put an end to
Obsolete usages often have hidden meanings about the thoughts and usage of words. In this case the obsolete usage renders a much clearer picture of words utter by our Lord on the Cross.
John 19:30 English Standard Version (ESV) When Jesus had received the sour wine, he said, “It is finished,” and he bowed his head and gave up his spirit.
One of the important benefits of the expiatory sacrifice of Christ on the Cross was putting an end to the obedience to the law as a means of being seen as righteous in God’s sight. We no longer have to perfectly obey all the law in order to be right with God.
The Old Testament issue of atonement was defined as a covering, not a removal. Sin became a thing hidden from God’s sight. Propitiation is not a covering, it is a substitution, a removal and casting away of sin and the designed replacement with the righteousness of God Himself in the person of Jesus Christ.
This is written without scriptural context. Does the Holy Spirit confirm this to be true? Each of us that have the abiding Spirit are able to confirm truth by virtue of agreement in the Spirit. Spirit speaks to Spirit by confirming truth.
Romans 9:1 English Standard Version (ESV) I am speaking the truth in Christ—I am not lying; my conscience bears me witness in the Holy Spirit—
Disciples require definitions, scriptures, teaching and at some point develop discernment. The mature Christian who has rightly divided the Word of truth is able to distinguish between truth and failed doctrine.