What is the ruling on one who says that any government that does not establish or rule by God's law is infidel and must be removed, citing Allah's saying: "The judgment is none but for Allah"?

There are two scenarios for ruling by other than what Allah has revealed: Either it is an act of denial or considering lawful what Allah has made unlawful, in which case it is major disbelief (kufr akbar). Or, it is an acknowledgment of the necessity to rule by what Allah has revealed, but one's desires overpower him in a specific issue, while he admits his error. In this case, it is minor disbelief (kufr asghar) and does not expel one from the fold of Islam. The first type includes those who legislate a law that permits the forbidden or forbids the permissible, or who approve of such a law and compel people to abide by it.