We were not discussing the dates of Yom Kippur, MP. You said that it doesn't exist in scripture. I showed you very clearly that it does. It was a DAY OF ATONEMENT. Atonement for SIN. The Jews had sin offerings to cover their failures, and even consecrate priests.
I'm sorry, but you don't have a scriptural leg to stand on with this. Sin IS in the Bible. Maybe Jews don't believe in the Christian concept of sin, but they still believe in sin. The word is discussed over and over again in the OT.
There are several Hebrew words that refer to sin. One is raah. It is used more than 600 times and means "evil" or "bad". According to Strong, it carries the implication of something that is contrary to God's nature.
Another is Chaaah. It's used 300 times and is usually translated "sin" or "offense". It carries the implication of that which is deserving of punishment.
Rasha is closely related and is used more than 250 times. It is usually translated "wicked". It carries the implication of something that is morally wrong.
Avon is used more than 200 times and is most often translated "iniquity". It carries the implication of being perverse, crooked, or twisted.
Perha is used 100 times and is translated "transgression". It carries the implication of REBELLION.
Asham is used more than 30 times and is translated as "guilty". It carries the implication of offense or tresspass.
There are several others, but I think you get the point. Sin is very present in the OT. And the Jews understood the need for the guilt of it to be removed in order to have a good standing before YHWH. Hence, the sacrifices.
Hebrews shows that these sacrifices pointed towards Jesus. Of course, modern non messianic Jews do not agree.