'Sincere' in the Bible
All these, being men of war arrayed in battle formation, came to Hebron with a perfect (committed) heart to make David king over all Israel; and all the rest of Israel were also of one mind to make David king.
Give sincere homage! Otherwise he will be angry, and you will die because of your behavior, when his anger quickly ignites. How blessed are all who take shelter in him!
For their heart was not steadfast toward Him,Nor were they faithful to His covenant.
How blessed and favored by God are those whose way is blameless [those with personal integrity, the upright, the guileless],Who walk in the law [and who are guided by the precepts and revealed will] of the Lord.
I will praise You with a sincere heartwhen I learn Your righteous judgments.
May my heart be blameless in Your statutes,So that I will not be ashamed.
Ointment and incense make the heart rejoice, likewise the sweetness of one's friend from sincere counsel.
The one who walks righteously and has spoken sincere words, who rejects gain from extortion and waves his hand, rejecting bribes, who blocks his ears from hearing plots of murder and shuts his eyes against seeing evil