Bible Verses About Sincerity: The preaching of the gospel

for we are not as the many, adulterating the word of God, but as of sincerity--but as of God; in the presence of God, in Christ we do speak.

for our exhortation is not out of deceit, nor out of uncleanness, nor in guile,

but as we have been approved by God to be entrusted with the good news, so we speak, not as pleasing men, but God, who is proving our hearts,

for at no time did we come with speech of flattery, (as ye have known,) nor in a pretext for covetousness, (God is witness!)