Contradiction with 1 John 4:12
1 John 4:12 states that no one has seen God at any time, which may contradict Paul's claim in 2 Corinthians 11:31 about God knowing the truth of his message.
1 John 4:12: No man hath seen God at any time. If we love one another, God dwelleth in us, and his love is perfected in us.
Contradiction with Exodus 33:20
God says that no one can see Him and live, while in 2 Corinthians 11:31, Paul emphasizes a personal knowledge of God that might imply a different level of direct interaction.
Exodus 33:20: And he said, Thou canst not see my face: for there shall no man see me, and live.
Contradiction with John 1:18
This verse mentions no one has seen God, which can be seen as contradictory to Paul's implications of knowing God’s witness in 2 Corinthians 11:31.
John 1:18: No man hath seen God at any time; the only begotten Son, which is in the bosom of the Father, he hath declared [him].
Contradiction with Isaiah 45:15
This verse describes God as one who hides himself, which could contrast with God's active witnessing role as mentioned in 2 Corinthians 11:31.
Isaiah 45:15: Verily thou [art] a God that hidest thyself, O God of Israel, the Saviour.