Bible Verses About Sincerity: The preaching of the gospel

For we are not as many, adulterating the word of God: but with sincerity: but as from God, before God, in Christ we speak.

For our exhortation was not of error, nor of uncleanness, nor in deceit.

But as we were approved by God that the gospel should be committed to us: even so we speak, not as pleasing men but God, who proveth our hearts.

For neither have we used at any time the speech of flattery, as you know: nor taken an occasion of covetousness (God is witness):