You are a priest forever, in the order of Melchizedek.

 Hebrew 7:1-28

Abraham gave him a tenth of everything. First, the name Melchizedek means “king of righteousness”; then also, “king of Salem” means “king of peace.” Without father or mother, without genealogy, without beginning of days or end of life, resembling the Son of God, he remains a priest forever. 

In the one case, the tenth is collected by people who die; but in the other case, by him who is declared to be living. One might even say that Levi, who collects the tenth, paid the tenth through Abraham, because when Melchizedek met Abraham, Levi was still in the body of his ancestor.

why was there still need for another priest to come, one in the order of Melchizedek, not in the order of Aaron? For when the priesthood is changed, the law must be changed also. He of whom these things are said belonged to a different tribe, and no one from that tribe has ever served at the altar. For it is clear that our Lord descended from Judah, and in regard to that tribe Moses said nothing about priests. And what we have said is even more clear if another priest like Melchizedek appears, one who has become a priest not on the basis of a regulation as to his ancestry but on the basis of the power of an indestructible life.

You are a priest forever, in the order of Melchizedek. 

The Lord has sworn and will not change his mind: ‘You are a priest forever.’ Because of this oath, Jesus has become the guarantor of a better covenant.

Such a high priest truly meets our need—one who is holy, blameless, pure, set apart from sinners, exalted above the heavens.

Why?

Paul explained from the Old Testament and the identity of Jesus Christ, that Jesus is a priest forever, in the order of Melchizedek, And he is not from man or human beings but came from heaven, like Melchizedek.

Because is the Son of the Lord so he came to the earth without father or mother, without genealogy, without beginning of day or end of life.

Because he is the Lord, the son of the Lord so Jesus came is out of human minds or imagination. And Jesus Christ is full of love and righteousness.

How?

Praise the Lord gave us Jesus Christ and let us get the eternal life through Jesus Christ.