The issue of conflicting authorities is explicitly covered in Scripture: Acts 5:29. If the state requires you to violate the 6th commandment, you are to obey God rather than man. Scripture interprets Scripture. The Scriptures (and Romans 13 in specific) say nothing about what form of government is required.

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Fredrick T. Greco
Senior Pastor, Christ Church PCA (Katy, TX)
Christ Church Blog

"The heart is the main thing in true religion...It is the hinge and turning-point in the condition of man's soul. If the heart is alive to God and quickened by the Spirit, the man is a living Christian. If the heart is dead and has not the Spirit, the man is dead before God." (J.C. Ryle)