Hebrews 5 1
Every high priest is a man chosen to represent other people in their dealings with God. He presents their gifts to God and offers sacrifices for their sins.
And he is able to deal gently with ignorant and wayward people because he himself is subject to the same weaknesses.
That is why he must offer sacrifices for his own sins as well as theirs.
And no one can become a high priest simply because he wants such an honor. He must be called by God for this work, just as Aaron was.
That is why Christ did not honor himself by assuming he could become High Priest. No, he was chosen by God, who said to him,
"You are my Son.
Today I have become your Father. 
And in another passage God said to him,
"You are a priest forever in the order of Melchizedek." 
While Jesus was here on earth, he offered prayers and pleadings, with a loud cry and tears, to the one who could rescue him from death. And God heard his prayers because of his deep reverence for God.
Even though Jesus was God's Son, he learned obedience from the things he suffered.
In this way, God qualified him as a perfect High Priest, and he became the source of eternal salvation for all those who obey him.
And God designated him to be a High Priest in the order of Melchizedek.
A Call to Spiritual Growth 11
There is much more we would like to say about this, but it is difficult to explain, especially since you are spiritually dull and don't seem to listen.
You have been believers so long now that you ought to be teaching others. Instead, you need someone to teach you again the basic things about God's word. 
You are like babies who need milk and cannot eat solid food.
For someone who lives on milk is still an infant and doesn't know how to do what is right.
Solid food is for those who are mature, who through training have the skill to recognize the difference between right and wrong.