Melchizedek has been mentioned three times, so far, in the book of Hebrews. Each time we are told that Jesus is a priest after the order of Melchizedek (5:6, 10; 6:20).
It is now time for the preacher to explain what he means. That is what he does in this 7th chapter. He explains how Jesus is a priest after the order of Melchizedek. In doing so he will accomplish two very specific things:
1) He will demonstrate, once again, the superiority of Jesus.
2) He will also answer how Jesus serves as a priest in a way that fulfills Old Testament promise.