Contradiction with Matthew 5:44
Psalms 51:13 speaks about teaching transgressors God's ways, whereas Matthew 5:44 instructs to love and bless enemies, focusing on love rather than teaching.
Matthew 5:44: But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;
Contradiction with Proverbs 23:9
Psalms 51:13 involves sharing wisdom with transgressors, while Proverbs 23:9 advises not to waste words on fools, suggesting not everyone is worth instructing.
Proverbs 23:9: Speak not in the ears of a fool: for he will despise the wisdom of thy words.
Contradiction with 1 Corinthians 2:14
Psalms 51:13 assumes sinners can understand God's ways when taught, but 1 Corinthians 2:14 states that the natural man doesn't accept spiritual truths.
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 Proverbs 9:7-8
Psalms 51:13 implies correcting sinners can lead to their conversion, whereas Proverbs 9:7-8 warns that correcting a wicked man can lead to insults and harm.
Proverbs 9:7-8: He that reproveth a scorner getteth to himself shame: and he that rebuketh a wicked [man getteth] himself a blot.