"But because Jesus lives forever, He has a permanent priesthood. Therefore He is able to save completely those who come to God through Him, because He always lives to intercede for them." Heb 7:24-25.

"For the law appoints as high priests men in all their weakness; but the oath, which came after the law, appointed the Son, who has been made perfect forever." Heb 7:28

The law (the Old Covenant) was a tutor until Christ came to save us completely. The ultimate and permanent priesthood (the New Covenant) was a better covenant. With the New Covenant, God's perfect law was written upon our hearts - and we are led by the Holy Spirit.