The actual word for Day of Atonement is Yom haKippurim and has no equivalent in English. It lost its meaning from Hebrew to English. It doesn’t mean “atonement” as understand by English speaking people.
HIS commands are clear and HE commands that we Worship Him in HIS way forever. If Yeshua (Jesus) was there in the beginning (John 1:1), then HE also helped pen the Old Testament. Through HIM it was written and HE knew one day HE would die to save us. HE gave the commands to keep the Feast Days FOREVER knowing HE would come back one day in the future and save mankind. Knowing this HE could have stated to keep the Feast Days “until I return”; HE did not state it that way.
Hebrews 4:15 shows us that our Messiah never sinned and followed the Feast Days. Acts 27:9 shows us it was being observed by early Christians. Paul shows us in Philippians 3:4-6 that he followed all the Feast Days. Paul also states in Acts 28:17 he was still following the customs of his ancestors, those customs were commanded by YHVH (God)…
Polycarp of Smyrna celebrated the Feast Days and is considered a saint in the Roman Catholic, Eastern Orthodox, Oriental Orthodox, Anglican, and Lutheran churches.