Contradiction with Jeremiah 17:9
This verse suggests the heart is deceitful, while 1 Thessalonians 2:3 claims their exhortation is without deceit.
Jeremiah 17:9: The heart [is] deceitful above all [things], and desperately wicked: who can know it?
Contradiction with Titus 1:10
This verse mentions there are many unruly and vain talkers and deceivers, which contrasts with the claim in 1 Thessalonians 2:3 of no deceit.
Titus 1:10: For there are many unruly and vain talkers and deceivers, specially they of the circumcision:
Contradiction with Romans 3:4
This verse indicates all men are liars, which could contradict the claim in 1 Thessalonians 2:3 that their message was not of deceit.
Romans 3:4: God forbid: yea, let God be true, but every man a liar; as it is written, That thou mightest be justified in thy sayings, and mightest overcome when thou art judged.
Contradiction with 1 Corinthians 1:17
This verse implies eloquent wisdom may lead to emptiness, contrasting with the genuine claim of exhortation in 1 Thessalonians 2:3.
1 Corinthians 1:17: For Christ sent me not to baptize, but to preach the gospel: not with wisdom of words, lest the cross of Christ should be made of none effect. [words: or, speech]
Contradiction with James 3:8
This verse suggests the tongue can be deceitful, which contradicts the idea of a speech given without deceit in 1 Thessalonians 2:3.
James 3:8: But the tongue can no man tame; [it is] an unruly evil, full of deadly poison.