Sincerity (572) (haplotes from a = negation + pleko = twine, braid, weave, knit) means singleness, simplicity, uprightness, mental honesty; the virtue of one who is free from pretence and dissimulation. Haplotes pertains to being motivated by singleness of purpose so as to be open and aboveboard, without guile, and without a hidden agenda. The idea of haplotes is that of personal integrity expressed in word or action. Expositor's Greek Testament notes that singleness of heart... states the spirit in which the obedience was to be rendered,—not in formality, pretence, or hypocrisy, but in inward reality and sincerity, and with an undivided heart” (Ephesians 6 Commentary) In the present verse haplotes means to obey with a heart fixed on pleasing Christ and not on worldly gain. What does haplotes heart look like in context? Ephesians 6:6 tells us that their heart is sincere because they are not obeying as an outward show that would conceal an inner improper motivation. In other words, when the Spirit filled slave obeys, it is not feigned obedience but genuine obedience. In other words haplotes means "what you see is what you get". Without pretense or ulterior motive. Not half-hearted. McGee says it... means there should not be any taint of duplicity. There should be no two-facedness. There should not be the licking of the boots of the employer when he is around and then stabbing him in the back when he is away. Such action should never be in the life of a Christian. (McGee, J V: Thru the Bible Commentary: Thomas Nelson) (Ephesians 6:5-9 Mp3 - Thru the Bible) As noted below in 3 uses in the second epistle to the Corinthians, haplotes also refers to an openness and sincerity in sharing with others. Haplotes is used 2 times in the Septuagint (LXX) and 8 times in the NT... 2 Samuel 15:11 Then two hundred men went with Absalom from Jerusalem, who were invited and went innocently (LXX = haplotes), and they did not know anything. 1 Chronicles 29:17 "Since I know, O my God, that Thou triest the heart and delightest in uprightness, I, in the integrity (LXX = haplotes) of my heart, have willingly offered all these things; so now with joy I have seen Thy people, who are present here, make their offerings willingly to Thee. Romans 12:8 (note) or he who exhorts, in his exhortation; he who gives, with liberality (haplotes); he who leads, with diligence; he who shows mercy, with cheerfulness. 2 Corinthians 1:12 For our proud confidence is this, the testimony of our conscience, that in holiness and godly sincerity (haplotes), not in fleshly wisdom but in the grace of God, we have conducted ourselves in the world, and especially toward you. 2 Corinthians 8:2 that in a great ordeal of affliction their abundance of joy and their deep poverty overflowed in the wealth of their liberality (haplotes). 2 Corinthians 9:11 you will be enriched in everything for all liberality (haplotes), which through us is producing thanksgiving to God...13 Because of the proof given by this ministry they will glorify God for your obedience to your confession of the gospel of Christ, and for the liberality (haplotes) of your contribution to them and to all, 2 Corinthians 11:3 But I am afraid, lest as the serpent deceived Eve by his craftiness, your minds should be led astray from the simplicity (haplotes) and purity of devotion to Christ. (Comment: Here haplotes describes a simple goodness, which gives itself without reserve, with no strings attached and with no hidden agenda.) Ephesians 6:5 Slaves, be obedient to those who are your masters according to the flesh, with fear and trembling, in the sincerity (haplotes) of your heart, as to Christ; Colossians 3:22 (note) Slaves, in all things obey those who are your masters on earth, not with external service, as those who merely please men, but with sincerity (haplotes) of heart, fearing the Lord.