1Cor.5.8  Let us, therefore, celebrate the festival, not with the old leaven, the leaven of malice and evil, but with the unleavened bread of sincerity and truth.
2Cor.1.12  For our boast is this, the testimony of our conscience that we have behaved in the world, and still more toward you, with holiness and godly sincerity, not by earthly wisdom but by the grace of God.
2Cor.2.17  For we are not, like so many, peddlers of God's word; but as men of sincerity, as commissioned by God, in the sight of God we speak in Christ.