Contradiction with Job 1:1
John 9:1 implies suffering due to sin, while Job 1:1 describes Job as righteous despite his suffering.
Job 1:1: There was a man in the land of Uz, whose name [was] Job; and that man was perfect and upright, and one that feared God, and eschewed evil.
Contradiction with Ezekiel 18:20
John 9:1 suggests the effects of sin from previous generations, contrasting with Ezekiel 18:20 which states that one will not bear the iniquity of another.
Ezekiel 18:20: The soul that sinneth, it shall die. The son shall not bear the iniquity of the father, neither shall the father bear the iniquity of the son: the righteousness of the righteous shall be upon him, and the wickedness of the wicked shall be upon him.
Contradiction with John 9:3
This verse directly counters John 9:1 by stating that the man's blindness was not due to sin.
John 9:3: Jesus answered, Neither hath this man sinned, nor his parents: but that the works of God should be made manifest in him.
Contradiction with Luke 13:2-3
Jesus refutes the idea that suffering is due to sinfulness in Luke, which contrasts with the implication in John 9:1.
Luke 13:2-3: And Jesus answering said unto them, Suppose ye that these Galilaeans were sinners above all the Galilaeans, because they suffered such things?