The Americans' rebellion from their lawful king was not in order to preach the gospel. Note that the apostles did not take up arms to overthrow the Romans or the Jews and Gentiles they had appointed to authority. The Zealots did try to overthrow the government. I suppose if someone really believes that scripture, rather than misinterpreting it to excuse rebellion, one would go North Korea or Iran and start preaching now.
Or, if one truly believes the USA is founded on ungodly motivations and anti-Biblical principles, they would renounce their citizenship and make themselves subject again to the monarch of England.