Sincerity
Sincerity means being the same inside as you appear outside. Paul writes, “Let love be without dissimulation,” and Peter speaks of “unfeigned love of the brethren.” Elsewhere Paul says he and his companions speak “as of sincerity, but as of God,” unlike those who corrupt the word of God. The Corinthians are told to keep the feast with “the unleavened bread of sincerity and truth.” Timothy’s faith is called unfeigned, first seen in his grandmother and mother. The psalmist describes the opposite, mouths with no faithfulness and flattering tongues. Romans 12 is a good place to start.
6 verses
Psalms
For there is no faithfulness in their mouth; their inward part is very wickedness; their throat is an open sepulchre; they flatter with their tongue.
Romans
Let love be without dissimulation. Abhor that which is evil; cleave to that which is good.
1 Corinthians
Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened bread of sincerity and truth.
2 Corinthians
For we are not as many, which corrupt the word of God: but as of sincerity, but as of God, in the sight of God speak we in Christ.
2 Timothy
When I call to remembrance the unfeigned faith that is in thee, which dwelt first in thy grandmother Lois, and thy mother Eunice; and I am persuaded that in thee also.
1 Peter
Seeing ye have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently: