'Sincerity' in the Bible

And, now, if in truth and in sincerity ye have acted, when ye make Abimelech king; and if ye have done good with Jerubbaal, and with his house; and if according to the deed of his hands ye have done to him --

yea, if in truth and in sincerity ye have acted with Jerubbaal and with his house this day, rejoice ye in Abimelech, and he doth rejoice -- even he -- in you;

so that we may keep the feast, not with old leaven, nor with the leaven of evil and wickedness, but with unleavened food of sincerity and truth.

For our glorying is this: the testimony of our conscience, that in simplicity and sincerity of God, not in fleshly wisdom, but in the grace of God, we did conduct ourselves in the world, and more abundantly toward you;

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.