Yom Kippur
This sixth feast is Israel's most awesome holy day. It occurs on the 10th of Tishri, nine days after the Feast of Trumpets. It was a day when the priesthood went through special cleansing and sanctification, when two goats were presented before the Lord; one was for YHWH (the LORD) and the other for azazel (for escape). The goat for YHWH was sacrificed and the scapegoat was let go into the wilderness after the sins of the people for that year were confessed over it.
The Ark of the covenant played a central role also, as this was the only day of the year when the High Priest entered the Holy of Holies to sprinkle blood on it. It marks a time of great repentance for the nation of Israel. They were to "afflict their souls". The blood of the sacrifice was sprinkled on the Ark as an atonement, which means covering. It represented the blood covering their sins. Even though this was done some 2000 years ago, it still must be acknowledged by each person. I believe this will happen as the nation of Israel sees Jesus their Messiah returning in great glory. "Look He is coming with the clouds, and every eye will see Him, even those who pierced Him; and all the people of the earth will mourn because of Him." (Rev. 1.7). Paul writes that all Israel will be saved, as in a day" (Rom. 11.26).