Kaisar (Καῖσαρ, G2541) is the Greek form of the Latin Caesar — the title of the Roman emperor. Originally the family name of Julius Caesar, it became the standard imperial title. The Caesars referenced in the New Testament include Augustus (Luke 2:1), Tiberius (Luke 3:1; 20:22–25), Claudius (Acts 11:28; 17:7; 18:2), and Nero (Acts 25:8–12; Philippians 4:22). 'Rendering to Caesar' and 'appealing to Caesar' are key New Testament moments where temporal and divine authority intersect.
Caesar (Kaisar) represents the totality of human imperial power in the New Testament — its reach, its claims, and its limits. Jesus' famous 'Give back to Caesar what is Caesar's, and to God what is God's' (Luke 20:25) does not merely validate taxation but establishes a dual-citizenship theology: Christians have obligations to earthly governments (Romans 13:1–7) while simultaneously belonging to a higher kingdom. Paul appeals to Caesar (Acts 25:11) — using Roman law as a protection for the gospel — demonstrating that earthly institutions can serve divine purposes. Yet Revelation (written under Domitian) presents Caesar-worship as the ultimate idolatry, and the martyrs die for refusing to say 'Caesar is Lord' (Kurios Kaisar) instead of 'Jesus is Lord' (Kurios Iesous). The tension between Caesar and Christ is the political spine of the New Testament.