Hebrews10, The Sacrifice for Sin

The sin offerings made in the tabernacle were only for unintentional sin and had to be repeated annually, because the people's hearts were not changed. Under the New Covenant God's law will be written on hearts of flesh instead of on tablets of stone. Thus, the offering Messiah made with His own blood needs only to have been done one time, since those cleansed by that offering will have had their hearts circumcised.