The principle duty of government is to secure the natural rights of the individual.
There is evil in this world and we must actively defend against it to secure the blessings of liberty. If there were no evil, there would be no need for government.
People are susceptible to corruption and government depends upon people to serve as officers. For this reason government offices are given limited jurisdiction and authority. This is known as federalism.
For example, the U.S. Federal Government is only authorized to perform 17 specific functions. Any other function is reserved to the States and the People. Within the Federal and State governments, jurisdictions and authority are further federated between legislative, executive and judicial branches. This structure is used to limit the ability of people serving in government from infringing upon the rights of the individual.
But federalism only works if the People, the States, and the different Offices within the government are true to their principle duty of protecting individual liberty.
The heart is deceitful above all things, and desperately wicked: who can know it?
Any man can withstand adversity; if you want to test his character, give him power.