Hebrews 7:17 in the King James Version of the Bible reads, "For he testifieth, Thou art a priest for ever after the order of Melchisedec." This verse comes in the context of the author of Hebrews explaining the superiority of Jesus' priesthood over the priesthood of the Levitical order. The author is making a case for Jesus being the ultimate and eternal high priest, in the order of Melchizedek, a priest-king who appears in the book of Genesis and is described in Psalm 110:4.

The use of the phrase "after the order of Melchisedec" in this verse is significant, as it signifies the eternal nature of Jesus' priesthood. In the Levitical priesthood, priests were established by genealogy and their service was limited by their mortal lifespan. However, the priesthood of Melchizedek, described in Psalm 110, is portrayed as an eternal priesthood. By aligning Jesus with this eternal priesthood, the author of Hebrews is emphasizing the eternal and unchanging nature of Jesus' role as our high priest.

The context of Hebrews 7:17 also includes a discussion of the Levitical priesthood's limitations and the necessity of a new and superior priesthood. The author explains that the old priesthood, with its system of animal sacrifices for sin, was insufficient to provide true and lasting atonement. But Jesus, as the high priest after the order of Melchizedek, offers a perfect and eternal atonement for sin through his own sacrificial death on the cross. This emphasizes the fulfillment and surpassing of the old system of priesthood with the new and better covenant established through Christ.

The theme of Jesus as the fulfillment of the Old Testament priesthood is central to this verse. In the Old Testament, the role of the high priest was to intercede for the people, offer sacrifices for sins, and maintain the covenant relationship between God and Israel. Jesus fulfills and surpasses this role as the ultimate high priest, interceding for believers before God and providing the perfect sacrifice for sin through his own death and resurrection.

The symbolism of the order of Melchizedek is also significant in understanding this verse. Melchizedek is a mysterious figure who appears in the book of Genesis as the king of Salem (which later became Jerusalem) and a "priest of God Most High" (Genesis 14:18). He blesses Abraham and receives tithes from him, and is described as having no recorded genealogy or end of life, making him a precursor to Jesus as an eternal priest-king.

The use of Melchizedek as a type or foreshadowing of Christ emphasizes the continuity and fulfillment of God's redemptive plan. Jesus' priesthood, as after the order of Melchizedek, is seen as superior to the Levitical priesthood and points to the perfection and completion of God's work of salvation. This symbolizes the eternal and unchanging nature of Jesus' priesthood, as well as his kingly authority and role as mediator between God and humanity.

In conclusion, Hebrews 7:17 in the King James Version of the Bible highlights the eternal nature and superiority of Jesus' priesthood as after the order of Melchizedek. It emphasizes the fulfillment and surpassing of the old system of priesthood, as well as the continuity and completeness of God's redemptive plan through Christ. This verse is a powerful declaration of Jesus' eternal role as our high priest and ultimate mediator, pointing to the perfect and unchanging nature of his atoning work for believers.