Contradiction with Matthew 12:31
This verse states that all manner of sin and blasphemy shall be forgiven unto men, which contradicts Mark 3:30 by suggesting broader forgiveness.
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 Luke 12:10
This verse indicates speaking a word against the Son of Man will be forgiven, which contrasts with the gravity of the unforgivable sin mentioned near Mark 3:30.
Luke 12:10: And whosoever shall speak a word against the Son of man, it shall be forgiven him: but unto him that blasphemeth against the Holy Ghost it shall not be forgiven.
Contradiction with 1 John 1:9
This verse promises that if we confess our sins, God is faithful to forgive us, which seems to conflict with the implication of an unforgivable sin in Mark 3:30.
1 John 1:9: If we confess our sins, he is faithful and just to forgive us [our] sins, and to cleanse us from all unrighteousness.
Contradiction with Hebrews 10:17
This verse declares God will remember sins and iniquities no more, potentially contradicting the idea of an unforgivable sin in Mark 3:30.
Hebrews 10:17: And their sins and iniquities will I remember no more. [And their: some copies have, Then he said, And their]
Contradiction with Romans 8:1
This verse proclaims no condemnation for those in Christ, which can contradict the notion of an eternal sin as implied in Mark 3:30.
Romans 8:1: [There is] therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.