The Pharisees could not wrap their heads around who Jesus is. He is the Son of Man who has the authority to forgive sins (which means that HE IS GOD!). He is the Friend of sinners and the Doctor to the sick. He is the Bridegroom of the Church, and His Spirit is the new wine. He is the Lord of the Sabbath - He is our rest. I don't think the Pharisees understood that He was fulfilling the old covenant and instituting and fulfilling the new covenant:
The author of Hebrews elaborates:
Heb. 7:11 So if the priesthood of Levi, on which the law was based, could have achieved the perfection God intended, why did God need to establish a different priesthood, with a priest in the order of Melchizedek instead of the order of Levi and Aaron?
12 And if the priesthood is changed, the law must also be changed to permit it. 13 For the priest we are talking about belongs to a different tribe, whose members have never served at the altar as priests. 14 What I mean is, our Lord came from the tribe of Judah, and Moses never mentioned priests coming from that tribe.
"You are a priest forever in the order of Melchizedek."
18 Yes, the old requirement about the priesthood was set aside because it was weak and useless. 19 For the law never made anything perfect. But now we have confidence in a better hope, through which we draw near to God.
Heavenly Father, you are holy and eternal. Your Word stands forever. Your salvation comes through faith in Jesus Christ, our great High Priest in the line of Melchizedek. Lord, I don't really understand it, but I know that you are awesome and mighty to save. May the power of Christ's life be poured into me and through me into the lives of others. May I serve you and honor you today. I ask in the name of Jesus Christ, my High Priest who brings me into fellowship with the One True God. Amen.