Expositor's Bible Commentary Commentary 1 Timothy 6:2

"And they that have believing masters, let them not despise them, because they are brethren; but let them serve them the rather, because they that partake of the benefit are believing and beloved. These things teach and exhort." — 1 Timothy 6:2 (ASV)

Not all Christian slaves had “believing masters.” But those who did were not “to show less respect [GK 2969] for them.” Instead, they were to serve them even better, realizing that they were benefiting their brothers in Christ; their masters were “dear to them” (lit., “beloved”; GK 28). This would give added incentive to their service.

The last sentence can be seen either as a specific instruction to Timothy about what to say to slaves, or else a general command regarding all that Paul has written to Timothy. Either makes good sense.