Slaves, be obedient to your human masters with fear and trembling. Today we encounter a passage that certainly makes modern readership uncomfortable, to say the least. Slavery has come to be regarded as an evil institution and a sin against the sacredness of the human person, and to think that Paul (or Christianity for that matter) could pronounce a statement that can even be remotely construed as supporting the institution of slavery is unsettling. However, Paul’s statement, as are the other unsettling numerous texts that are spread throughout the sacred Scriptures, need to be read and interpreted in the context in which it was made in order to fully understand the teaching it was meant to convey. 
Beginning in the fifteenth verse of chapter five (through chapter 6:9), Paul addresses life in Christ in a Christian community (both in the home/household and the larger community). Using the Trinity as an example, Paul reminds the Ephesians that Christian life is one of subordination, not of hierarchy to which they were used, but rather of service in love. As a people who had been baptized in Christ, Paul wanted to call to their attention the fact that they had accepted to let their lives be shaped by the values of Christ. The greatest value that the baptized had to espouse is a life of subordination in love and service. A slave whose life consisted in serving his/master out of fear was to continue serving his master, not out of fear but out of love for Christ. A master was to desist from looking upon his servant as a slave, as somebody who was working for him out of fear and instead to see in him a fellow brother serving him in love.