“Bondservants, obey in all things your masters according to the flesh, not with eyeservice, as men-pleasers, but in sincerity of heart, fearing God.”
“but in sincerity of heart”
“Sincerity of heart” means simplicity, sincerity, uprightness, frankness. “Sincerity” first meant “simple” and then it came to mean “open.” It means no ulterior motive. God wants us to work out of a motivation of a genuine heart. This goes beyond working to impress the boss. This person operates with pure motives, singleness of purpose (Eph. 6:5).
“Fearing God” means we work out of a respect for God. God wants us to work at our employment as if we were working for God.
We are under the surveillance of God every moment. The quality of our work should reflect that God is watching. One of the names of God in the Old Testament is El Roi, “the God who sees.” He is watching whether your employer is in sight or not.
The Christian serves his employer from an inner monitor, the monitor of character.
The Christian works from character; he is reliable and trustworthy under any circumstance whether anyone is watching or not. That is what makes the difference between a Christian and a non-Christian at work.