Contradiction with Proverbs 26:4
This verse advises not to answer a fool according to his folly, which could be seen to contradict the idea of straightforward communication expressed in 2 Corinthians 1:13.
Proverbs 26:4: Answer not a fool according to his folly, lest thou also be like unto him.
Contradiction with Matthew 13:11
This verse shows that Jesus spoke in parables to some people, implying that not everything is straightforward, which can be seen as a contradiction to the clarity mentioned in 2 Corinthians 1:13.
Matthew 13:11: He answered and said unto them, Because it is given unto you to know the mysteries of the kingdom of heaven, but to them it is not given.
Contradiction with John 16:25
Jesus speaks of using figures of speech instead of plain language, which could contradict the straightforward writing referenced in 2 Corinthians 1:13.
John 16:25: These things have I spoken unto you in proverbs: but the time cometh, when I shall no more speak unto you in proverbs, but I shall shew you plainly of the Father. [proverbs: or, parables]
Contradiction with 1 Corinthians 2:14
This verse suggests that spiritual truths can be complex and not easily understood by everyone, contradicting the notion of clarity in 2 Corinthians 1:13.
1 Corinthians 2:14: But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know [them], because they are spiritually discerned.
Contradiction with 2 Peter 3:16
It notes that some scriptures are hard to understand, which may contrast with the straightforward message mentioned in 2 Corinthians 1:13.
2 Peter 3:16: As also in all [his] epistles, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as [they do] also the other scriptures, unto their own destruction.