In Exodus 20:3 we read: "Thou shalt have no other gods before me." One could interpret this to mean, that within the society that you reside, the highest power in authority should be God, who shalt rule over his people. That is to say, if one wishes to truly adhere to this Commandment, a valid argument can be made, that God's law trumps all. This, in fact, encompasses the very basis of natural law, which is right reason, revealed, and applicable to all, which is the foundation of Western Civilization.
This would thereby imply to a significant degree, that the best form of Government is some form of a Theocracy or something similar that recognizes that God's law is the best form of law because, by definition, it is morally correct, immutable, applicable to all beings, and for the common good. On the other hand, while man's law can be equally good and well applied, it is also subject to being corrupted, incorrect, wrongly applied, and a form of injustice under the guise of justice.
In today's word there are only a few countries that are Theocratic, to which, with the exception of the small city-state of Vatican City, which is Roman Catholic, the balance of all others such as Iran, Saudi Arabia, and the Sudan, are all Islamic. Unfortunately, Theocracies of today are, for the most part, oppressors of their subjects, arbitrary, capricious, autocratic, and suppressive. To make matters worse, because they are Theocracies, there is little in their mindset to satiate their lusts in submitting their people to the sword of their wrongly applied Divine Justice. This then makes a strong case that in unprincipled Theocracies, the people are in the most abject position, because when having to deal with the consequences of injustice, their appeal to the Highest Court, which is God himself, is subverted by the State.
Generally, the best Government for the people is a government that allows its citizens their freedom of conscience as to how they wish to submit themselves or to profess themselves to their faith. This basically means, that the conception of the United States and similar countries, to which the people are afforded the free exercise of their religious persuasion without State interference or intervention is the ideal condition to which all may be afforded the opportunity to follow the Biblical command to have no other god.
Having said this, many modern western civilizations are increasingly becoming closer and closer to essentially secular states that actively oppose God and His commandments, by allowing the State, alone, to rule all as it sees fit. The problem as seen by too many countries, today, is that they do not want their subjects to even conceive that there could possibly be a Higher Authority that they should consider answering a call to. The State, in many nations today, wants to, in principle, to be the god to their people, and therefore it follows that they want their people to have no other gods but the State. This is the reason why the State is so insistent, in so many cases, to stridently state that it's only fair and right that there should be a wall of separation between Church and State.
If, in fact, God is eliminated from the public square, that God Himself is eliminated from governmental principles, there will be nothing, absolutely nothing that the State will not be permitted to do against its own subjects in its tyrannical possession of them for their own nefarious means.