Contradiction with Romans 6:23
This verse states that the wages of sin is death, implying that all sin leads to death, which contrasts with the promise in John 8:51 of not seeing death for those who keep Jesus' sayings.
Romans 6:23: For the wages of sin [is] death; but the gift of God [is] eternal life through Jesus Christ our Lord.
Contradiction with Hebrews 9:27
It is appointed for men to die once, which contradicts the idea that anyone can avoid death, as suggested in John 8:51.
Hebrews 9:27: And as it is appointed unto men once to die, but after this the judgment:
Contradiction with Ecclesiastes 9:5
This verse implies that the living know they shall die, contrasting with John 8:51's implication of not experiencing death.
Ecclesiastes 9:5: For the living know that they shall die: but the dead know not any thing, neither have they any more a reward; for the memory of them is forgotten.
Contradiction with Psalm 89:48
This verse questions if any man can avoid seeing death, contradicting the assurance in John 8:51.
Psalm 89:48: What man [is he that] liveth, and shall not see death? shall he deliver his soul from the hand of the grave? Selah.
Contradiction with Job 14:1-2
Job describes life as brief and ending in death for all, conflicting with the promise in John 8:51.
Job 14:1-2: Man [that is] born of a woman [is] of few days, and full of trouble. [few...: Heb. short of days]