Lordship of Christ

"Therefore God has highly exalted him and bestowed on him the name that is above every name, so that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father." - Philippians 2:9-11

The Greek word for Lord is kurios, the word used by citizens of the Roman empire to acknowledge the divinity of Caesar. This title was never used of the emperors until they were thought to be deified through a religious ceremony; therefore, it was used as a divine title. Within the empire there was a test phrase used to check the loyalty of the people. It was Kyrios Kaiser, and it meant “Caesar is Lord.” Christians who would not say these words were later singled out from pagans and executed. In those days when a Christian insisted that Jesus is Lord he meant that Jesus, not Caesar, is divine. The same meaning is present when the word occurs in Hebrew, only more so. The Hebrew word is Adonai. It is a title somewhat like our “sir,” but it assumed an extraordinary importance in Hebrew speech because in practice it replaced the personal name of God, Jehovah. No Jew pronounced the word “Jehovah,” even when reading the Bible. Instead he said, “Adonai.”
- Boice, J. M.. Philippians : An Expositional Commentary. Grand Rapids, Mich.: Baker Books)