I think you really should look this up, because it wasn't because they became Christian, that's just discriminatory. It was because they forced everyone to follow one religion, which is completely different. They took away people's right to freedom of religion. America is certainly NOT based on that. America was based on the Roman justice system. It was not based on Rome itself, with possibly the exception of architecture, but even then we have our own style.
Also, those other countries had just as big an influence as Rome did. The idea of a limited government came from England, as they were the first to have a limited government. Also, YES France, because they had VERY similar laws to England, not to mention they had their own revolution after ours to get a limited government. America looked to see what worked.
Also, I can't just LEAVE a country as a minor first of all, as I'm not going to throw away my education, and sneak into another country. I plan on doing it the legal and smart way. Saving money, having a good education under my belt, and going through customs, as my parents don't simply move to another country to please me, nor do I ask that of them.
By the way, that just says it didn't include Rome in it's borders, it's referring to the CITY of Rome. The empire was the remains of what used to be the Roman empire, the part with Rome became the Byzantine Empire.