Bible Verses About Sincerity: The preaching of the gospel

For we are not as the many, corrupting the word of God: but as of sincerity, but as of God, in the sight of God, speak we in Christ.

For our exhortation is not of error, nor of uncleanness, nor in guile:

but even as we have been approved of God to be intrusted with the gospel, so we speak; not as pleasing men, but God who proveth our hearts.

For neither at any time were we found using words of flattery, as ye know, nor a cloak of covetousness, God is witness;