Contradiction with Hebrews 10:26-27
These verses suggest that there is no forgiveness for willful sin after knowing the truth, which contradicts Mark 3:28's assurance of forgiveness for all sins.
Hebrews 10:26-27: For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
Contradiction with Matthew 12:31
This verse states that blasphemy against the Holy Spirit shall not be forgiven, contradicting the notion in Mark 3:28 that all sins shall be forgiven.
Matthew 12:31: Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy [against] the [Holy] Ghost shall not be forgiven unto men.
Contradiction with 1 John 5:16
Implies that there is sin leading to death which should not be prayed for, suggesting such sins may not be forgiven, contradicting Mark 3:28's promise of forgiveness for all sins and blasphemies.
1 John 5:16: If any man see his brother sin a sin [which is] not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it.