'Order of Melchizedek' in the Bible

Now if perfection [a perfect fellowship between God and the worshiper] had been attained through the Levitical priesthood (for under it the people were given the Law) what further need was there for another and different kind of priest to arise, one in the manner of Melchizedek, rather than one appointed to the order of Aaron?

(for those Levites who formerly became priests [received their office] without [its being confirmed by the taking of] an oath, but this One [was designated] with an oath through the One who said to Him,“The Lord has swornAnd will not change His mind or regret it,‘You (Christ) are a Priest forever’”).