Luke 20:25
25 And He said unto them, "Then render unto Caesar the things that are Caesar's, and unto God the things that are God's."
ASV
Some try to claim Jesus meant we are to keep a separation between Church and state by what He said, but He never implied any such idea.
And it's amazing too that Christ's enemies, especially Communism, likes to try and push that false political disinformation about the idea of separation of Church and state.
Reason is, that when Lord Jesus said the above, the children of Israel were still under the old covenant law. And religious worship was a commandment, a requirement instituted by the then authorities per the law. So how's that for some idea that Jesus meant to separate Church from the state?
The 1st Amendment of the U.S. Constitution says, "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof;".
That means there is no such thing as a political separation of Church and state written in the U.S. Constitution. Instead, the U.S. Constitution protects the freedom of religious worship, and is not even to meddle in the affairs of religious worship. This is because the U.S. Founders did not establish a Theocracy, which for example, Israel under the old covenant was. The Catholic nations in Europe also were Theocracies, the Christian Church pretty much reigned together with the royals.