When Jesus said, “Render unto Caesar the things that are Caesar’s, and unto God the things that are God’s,” He was telling us that there is a clear separation between the church and the state. The church should not overlay its directives onto the government; likewise, the government should stay out of the church’s business. (“Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof.” [1st Amendment to the Constitution, first clause])
He did not command His followers to enshrine their beliefs in any government’s laws, and we should not do so. The church and the government serve two entirely different purposes: One is to prepare us for the kingdom of God, and the other is to help us govern ourselves here on Earth in a manner that is peaceful, respectful and for the good of us all — regardless of one’s religious beliefs.