Contradiction with James 2:24
This verse highlights that a person is justified by works and not faith only, contradicting the emphasis on "faith" as good tidings brought by Timothy in 1 Thessalonians 3:6.
James 2:24: Ye see then how that by works a man is justified, and not by faith only.
Contradiction with Galatians 1:6-7
Paul expresses astonishment at the Galatians turning to a different gospel, indicating instability in faith, which contrasts the report of strong faith in 1 Thessalonians 3:6.
Galatians 1:6-7: I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel:
Contradiction with Matthew 7:21
Not everyone who professes faith will enter Heaven, contrasting the positive account of faith in 1 Thessalonians 3:6 by hinting profession alone isn't enough.
Matthew 7:21: Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
Contradiction with Revelation 2:4
The mention of losing one's first love contradicts the steadfast remembrance and faith noted in 1 Thessalonians 3:6.
Revelation 2:4: Nevertheless I have [somewhat] against thee, because thou hast left thy first love.