Civil government exists to protect us, its citizens, from our enemies-- whether at home or abroad-- so that we can get down to the business of making something of ourselves.
It is also important to remember that, in its very nature, government is extremely vulnerable to corruption-- whether that government is red, blue, yellow, orange, or purple with pink polka dots. This is true at any level.
As Lord Acton (1834-1902) put it:
"Power tends to corrupt, and absolute power corrupts absolutely. Great men are almost always bad men."
Almost always, okay? Not always. But very, very often. A great, good man is quite rare. (And I use the term 'man' in the universal sense.)
William Pitt talked about unlimited power in 1770:
"Unlimited power is apt to corrupt the minds of those who possess it"
This is why the founding fathers of the United States designed a limited government. They understood that power is terribly vulnerable to corruption by sinful men.
Why do we have civil government, then? Because not enough of us have personal government; we do not govern our own selves well. This is the reason for crime and war.
It has been my experience (and is my understanding from studying history) that the bigger civil government gets, the less individuals are spurred toward personal government. This is why I do not agree with big government.
We do not have a king, nor do we want one, because of the corrupting influence of power. The "Divine Right of Kings" was a myth. There is only one King who has a Divine Right. This is why a representative democracy, or a democratic republic (we can parse those terms later), is the best government model put forth thus far. None of us are trustworthy when given too much power (not even a mob of "ordinary" people). Therefore, we have a government that by its very nature discourages government action and encourages an individual's dependence on himself.