Gk. Christianos, a word formed from Latin. The ending ianos, denoting an adherent of someone, was applied to slaves belonging to the great families in the Roman Empire. One who worshipped the emperor, the Caesar, or Kaisar, was called Kaisarianos, which means an adherent of Kaisar, a person who belongs to Kaisar. When people believed in Christ and became His followers, some in the Empire came to consider Christ a rival of their Kaisar. Then, at Antioch (Acts 11:26) they began to call the followers of Christ Christianoi (Christians), adherents of Christ, as a nickname, a term of reproach. Hence, this verse says, "As a Christian, let him not be ashamed"; that is, if any believer suffers at the hands of the persecutors who contemptuously call him a Christian, he should not feel ashamed but should glorify God in this name.
Today the term Christian should bear a positive meaning, that is, a man of Christ, one who is one with Christ, not only belonging to Him but also having His life and nature in an organic union with Him, and who is living by Him, even living Him, in his daily life. If we suffer for being such a person, we should not feel ashamed but should be bold to magnify Christ in our confession by our holy and excellent manner of life to glorify (express) God in this name.