Contradiction with 1 Samuel 2:35
1 Samuel 2:35 speaks of a singular, enduring priest, whereas Hebrews 7:23 discusses the many priests due to death preventing them from continuing.
1 Samuel 2:35: And I will raise me up a faithful priest, [that] shall do according to [that] which [is] in mine heart and in my mind: and I will build him a sure house; and he shall walk before mine anointed for ever.
Contradiction with John 12:34
John 12:34 suggests an everlasting leader, contrasting the transient nature of priests in Hebrews 7:23.
John 12:34: The people answered him, We have heard out of the law that Christ abideth for ever: and how sayest thou, The Son of man must be lifted up? who is this Son of man?
Contradiction with Hebrews 10:12
Hebrews 10:12 highlights a single sacrifice made by one priest forever, in contrast to the multiple priests in Hebrews 7:23.
Hebrews 10:12: But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God;
Contradiction with Psalm 110:4
Psalm 110:4 asserts an eternal priesthood for one, challenging the repeated succession of priests in Hebrews 7:23.
Psalm 110:4: The LORD hath sworn, and will not repent, Thou [art] a priest for ever after the order of Melchizedek.
Contradiction with Genesis 14:18
Melchizedek is presented without mention of succession, in contradiction to the notion of multiple priests mentioned in Hebrews 7:23.
Genesis 14:18: And Melchizedek king of Salem brought forth bread and wine: and he [was] the priest of the most high God.