Fausset's Bible Dictionary
The common title of the successive Roman emperors, taken from Julius Caesar. In the New Testament Augustus in Luke 2:1, Tiberius in Luke 3:1, Claudius in Acts 11:28, Nero in Acts 25:11, etc. Roman citizens as Paul had the right of "appeal to Caesar," and in criminal cases were sent for judgment to Rome, where was the emperor's court (Philippians 4:22; compare Philippians 1:13); Nero is the emperor meant. John's exile to Patmos (Revelation 1:9) was probably in Domitian's reign. The current coin bore Caesar's image, the argument which Jesus used to show Caesar could claim tribute (Matthew 22:17, etc.). Though Caesar did not call himself "king," the Jews did (John 19:15), in which respect Josephus (B. J. 5:2, section 2) confirms the gospel undesignedly.
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Fausset, Andrew R. Entry for 'Caesar'. Fausset's Bible Dictionary. https://www.studylight.org/dictionaries/eng/fbd/c/caesar.html. 1949.