Law and Gospel have differences.
In the OT, the Law was intended to drive God’s people to repentance and to purify the people he chose to bring forth His messiah. Governments over the Hebrews, both good and bad,were established for specific purposes.
Once the messiah was brought forth, the Gospel reigned and civil/political government was given to The Church to support the Gospel.
If a government does not support the Christian liberty found in the Gospel, it is not legitimately given by God...it is legitimate in that it is allowed to exist according to the tolerance of The Church.
And people forget that the U.S. is unique in that it is supposed to be a “government of and by the people”. I do not serve an emperor.