'Sincerity' in the Bible

“Now, therefore, fear the Lord and serve Him in sincerity and in truth; remove the gods which your fathers served on the other side of the [Euphrates] River and in Egypt, and serve the Lord.

“My words will express the uprightness of my heart,And my lips will speak what they know with utter sincerity.

The Lord dealt with me according to my righteousness (moral character, spiritual integrity);According to the cleanness of my hands He has rewarded me.

“Hear this, O house of Jacob, you who are called by the name of IsraelAnd who come from the seed of Judah,You who swear [allegiance] by the name of the LordAnd invoke the God of Israel,But not in truth (sincerity) nor in righteousness [with moral and spiritual integrity].

Yet in spite of all this her treacherous sister Judah did not return to Me with her whole heart, but rather in [blatant] deception [she merely pretended obedience to King Josiah’s reforms],” declares the Lord.

“Roam back and forth through the streets of Jerusalem,And look now and take note.And look in her open squaresTo see if you can find a man [as Abraham sought in Sodom],One who is just, who [has integrity and moral courage and] seeks truth (faithfulness);Then I will pardon Jerusalem—[for the sake of one uncompromisingly righteous person].